Updated SDK download instructions. (Ported changes from DevSite.)

native_client_sdk/src/doc/sdk/download.rst

 .. _download:
 
 Download the Native Client SDK
 ==============================
 
-Follow the steps below to download and install the SDK:
+To build Native Client modules, you must download and install the Native
+Client Software Development Kit (SDK). This page provides an overview
+of the Native Client SDK, and instructions for how to download and
+install the SDK.
+
+Overview
+--------
+
+The Native Client SDK includes the following:
+
+support for multiple Pepper versions
+  The SDK contains **bundles** that let you compile Native Client modules
+  using different versions of the
+  :ref:`link_pepper` (e.g., Pepper 31 or Pepper Canary). Review the
+  :doc:`Release Notes <release-notes>` for a description of the new features
+  included in each Pepper version to help you decide which bundle to
+  use to develop your application. In general, Native Client modules
+  compiled using a particular Pepper version will work in
+  corresponding versions of Chrome and higher. For example, a module
+  compiled using the Pepper 31 bundle will work in Chrome 31 and
+  higher.
+
+update utility
+  The ``naclsdk`` utility (``naclsdk.bat`` on Windows) lets you download new
+  bundles that are available, as well as new versions of existing bundles.
+
+toolchains
+  Each platform includes three toolchains: one for compiling
+  Portable Native Client (PNaCl) applications, one for compiling
+  architecture-specific Native Client applications with newlib, and
+  one for compiling architecture-specific Native Client applications with glibc.
+  Newlib and glibc are two different implementations
+  of the C standard library. All three toolchains contain
+  Native Client-compatible versions of standard compilers, linkers,
+  and other tools. See :doc:`NaCl and PNaCl </nacl-and-pnacl>` to help
+  you choose the right toolchain.
+
+examples
+  Each example in the SDK includes C or C++ source files and header files
+  illustrating how to use NaCl and Pepper, along with a Makefile to build
+  the example using each of the toolchains.
+
+tools
+  The SDK includes a number of additional tools that you can use for
+  tasks such as validating Native Client modules and running modules
+  from the command line.
+
+Follow the steps below to download and install the Native Client SDK.
 
 Prerequisites
 -------------
 
-* Python: Make sure you have Python 2.6 or 2.7 installed, and that the Python
-  executable is in your path.
+* **Python:** Make sure you have Python 2.6 or 2.7 installed, and that the
+  Python executable is in your path.
 
-  * On Mac/Linux, Python is probably preinstalled. Run the command ``"python
+  * On Mac/Linux, Python is likely preinstalled. Run the command ``"python
     -V``" in a terminal window, and make sure that the version of Python you
     have is 2.6.x or 2.7.x (if it's not, upgrade to one of those versions).
   * On Windows, you may need to install Python. Go to
     `http://www.python.org/download/ <http://www.python.org/download/>`_ and
     select the latest 2.x version. In addition, be sure to add the Python
     directory (for example, ``C:\python27``) to the PATH `environment
     variable <http://en.wikipedia.org/wiki/Environment_variable>`_. After
     you've installed Python, run the command ``"python -V``" in a Command
     Prompt window and verify that the version of Python you have is 2.6.x or
     2.7.x.
   * Note that Python 3.x is not yet supported.
 
-* Make: On the Mac, you need to install the ``make`` command on your system before
-  you can build and run the examples. One easy way to get ``make``, along
-  with several other useful tools, is to install `Xcode Developer Tools
-  <https://developer.apple.com/technologies/tools/>`_. After installing
-  Xcode, go to the Preferences menu, select Downloads and Components, and
-  verify that Command Line Tools are installed. If you'd rather not install
-  Xcode, you can download and build an `open source version
+* **Make:** On the Mac, you need to install the ``make`` command on your system
+  before you can build and run the examples in the SDK. One easy way to get
+  ``make``, along with several other useful tools, is to install
+  `Xcode Developer Tools <https://developer.apple.com/technologies/tools/>`_.
+  After installing Xcode, go to the Preferences menu, select
+  Downloads and Components, and verify that Command Line Tools are installed.
+  If you'd rather not install Xcode, you can download and build an
+  `open source version
   <http://mac.softpedia.com/dyn-postdownload.php?p=44632&t=4&i=1>`_ of
-  ``make``.  In order to build the command you may also need to download and
-  install a copy of `gcc
-  <https://github.com/kennethreitz/osx-gcc-installer>`_.
+  ``make``. In order to build the command you may also need to download and
+  install a copy of `gcc <https://github.com/kennethreitz/osx-gcc-installer>`_.
 
-Download Steps
---------------
+Download and install the SDK
+----------------------------
 
 #. Download the SDK update utility: `nacl_sdk.zip
    <http://storage.googleapis.com/nativeclient-mirror/nacl/nacl_sdk/nacl_sdk.zip>`_.
 
 #. Unzip the SDK update utility:
 
-   * On Mac/Linux, run the command "``unzip nacl_sdk.zip``" in a Terminal window.
+   * On Mac/Linux, run the command "``unzip nacl_sdk.zip``" in a terminal
+     window.
    * On Windows, right-click on the .zip file and select "Extract All...". A
      dialog box will open; enter a location and click "Extract".
 
    Unzipping the SDK update utility creates a directory called ``nacl_sdk`` with
    the following files and directories:
 
    * ``naclsdk`` (and ``naclsdk.bat`` for Windows) --- the front end of the update
      utility, i.e., the command you run to download the latest bundles
-   * ``sdk_cache`` --- a directory with a manifest file that lists the bundles you
-     have already downloaded
+   * ``sdk_cache`` --- a directory with a manifest file that lists the bundles
+     you have already downloaded
    * ``sdk_tools`` --- the back end of the update utility, also known as the
      "sdk_tools" bundle
 
-#. See which SDK versions are available: Go to the ``nacl_sdk`` directory and
-   run ``naclsdk`` with the ``"list"`` command to see a list of available bundles.
-   The SDK includes a separate bundle for each version of Chrome/Pepper
-   (see versioning information).
+#. To see the SDK bundles that are available for download, go to the ``nacl_sdk``
+   directory and run ``naclsdk`` with the ``"list"`` command.
+   The SDK includes a separate bundle for each version of Chrome/Pepper.
 
    On Mac/Linux::
 
      $ cd nacl_sdk
      $ ./naclsdk list
 
    On Windows::
 
      > cd nacl_sdk
      > naclsdk list
 
    You should see output similar to this::
 
     Bundles:
      I: installed
      *: update available
 
       I  sdk_tools (stable)
          vs_addin (dev)
-         pepper_26 (post_stable)
          pepper_27 (post_stable)
          pepper_28 (post_stable)
          pepper_29 (post_stable)
-         pepper_30 (stable)
-         pepper_31 (beta)
+         pepper_30 (post_stable)
+         pepper_31 (stable)
+         pepper_32 (beta)
          pepper_canary (canary)
 
-   This sample output shows many bundles available for download, and that you
-   have already installed the latest revision of the sdk_tools bundle (it was
-   included in the zip file you downloaded). Note that the bundles are labelled
-   "post-stable", "stable", "beta", "dev" and "canary". These labels correspond
-   to the current versions of Chrome. In this example, Chrome 30 is stable,
-   Chrome 31 is beta, etc. Therefore ``pepper_30`` is the recommended bundle to
-   download, because if you released an application that used it today, it
-   could be used by all current Chrome users. Note that Native Client is
-   designed to be backward compatible---users of Chrome 31 can use the features
-   of ``pepper_30`` and earlier.
+   The sample output above shows that there are a number of bundles available
+   for download, and that you have already installed the latest revision of the
+   ``sdk_tools`` bundle (it was included in the zip file you downloaded).
+   Each bundle is labeled post-stable, stable, beta, dev, or canary.
+   These labels usually correspond to the current versions of
+   Chrome. (In the example above, Chrome 31 is stable, Chrome 32 is beta, etc.).
+   We generally recommend that you download and use a "stable" bundle,
+   as applications developed with "stable" bundles can be used by all current
+   Chrome users. This is because Native Client is designed to be
+   backward-compatible (for example, applications developed with the
+   ``pepper_31`` bundle can run in Chrome 31, Chrome 32, etc.).
+   Thus in the example above, ``pepper_31`` is the recommended bundle to use.
 
-#. Run ``naclsdk`` with the "update" command to download particular bundles that
-   are available.
+#. Run ``naclsdk`` with the "update" command to download recommended bundles.
 
    On Mac/Linux::
 
      $ ./naclsdk update
 
    On Windows::
 
      > naclsdk update
 
-   By default, ``naclsdk`` only downloads bundles that are recommended.  In
-   general, only the "stable" bundles are recommended. Continuing with the
-   earlier example, the "update" command would only download the ``pepper_30``
-   bundles, since the bundles ``pepper_31`` and greater are not yet recommended.
-   If you want the ``pepper_31`` bundle, you must ask for it explicitly::
+   By default, ``naclsdk`` only downloads bundles that are
+   recommended---generally those that are "stable." Continuing with the earlier example, the
+   "update" command would only download the ``pepper_31``
+   bundle, since the bundles ``pepper_32`` and greater are not yet stable.
+   If you want the ``pepper_32`` bundle, you must ask for it explicitly::
 
-     $ ./naclsdk update pepper_31
+     $ ./naclsdk update pepper_32
 
-   Note that you never need update the ``sdk_tools`` bundle, it is
-   updated automatically as necessary whenever ``naclsdk`` is run.
+   Note that you never need to update the ``sdk_tools`` bundle---it is
+   updated automatically (if necessary) whenever you run ``naclsdk``.
 
 .. Note::
   :class: note
 
-  The minimum SDK version that supports PNaCl is ``pepper_31``.
+  The minimum SDK bundle that supports PNaCl is ``pepper_31``.
 
-Staying up-to-date and getting new versions
--------------------------------------------
+Staying up-to-date and getting new versions of bundles
+------------------------------------------------------
 
 #. Run ``naclsdk`` with the "list" command again; this will show you the list of
-   available bundles and verify which bundles are installed.
+   available bundles and verify which bundles you have installed.
 
    On Mac/Linux::
 
      $ ./naclsdk list
 
    On Windows::
 
      > naclsdk list
 
    Continuing with the earlier example, if you previously downloaded the
-   ``pepper_30`` bundle, you should see output similar to this::
+   ``pepper_31`` bundle, you should see output similar to this::
 
     Bundles:
      I: installed
      *: update available
 
       I  sdk_tools (stable)
          vs_addin (dev)
-         pepper_26 (post_stable)
          pepper_27 (post_stable)
          pepper_28 (post_stable)
          pepper_29 (post_stable)
-      I  pepper_30 (stable)
-         pepper_31 (beta)
+         pepper_30 (post_stable)
+      I  pepper_31 (stable)
+         pepper_32 (beta)
          pepper_canary (canary)
 
 #. Running ``naclsdk`` with the "update" command again will verify that your
    bundles are up-to-date, or warn if you there are new versions of previously
    installed bundles.
 
    On Mac/Linux::
 
      $ ./naclsdk update
 
    On Windows::
 
      > naclsdk update
 
    Continuing with the earlier example, you should see output similar to this::
 
-     pepper_30 is already up-to-date.
+     pepper_31 is already up-to-date.
 
 #. To check if there is a new version of a previously installed bundle, you can
    run the "list" command again::
 
     Bundles:
      I: installed
      *: update available
 
       I  sdk_tools (stable)
          vs_addin (dev)
-         pepper_26 (post_stable)
          pepper_27 (post_stable)
          pepper_28 (post_stable)
          pepper_29 (post_stable)
-      I* pepper_30 (stable)
-         pepper_31 (beta)
+         pepper_30 (post_stable)
+      I* pepper_31 (stable)
+         pepper_32 (beta)
          pepper_canary (canary)
 
-   The asterisk next to the bundle name indicates that there is an update
-   available. If you run  the "update" command now, ``naclsdk`` will warn you
-   with a message similar to this::
+   An asterisk next to a bundle indicates that there is an update
+   available for that bundle. If you run  the "update" command now,
+   ``naclsdk`` will warn you with a message similar to this::
 
-     WARNING: pepper_30 already exists, but has an update available.
+     WARNING: pepper_31 already exists, but has an update available.
      Run update with the --force option to overwrite the existing directory.
      Warning: This will overwrite any modifications you have made within this directory.
 
    To dowload the new version of a bundle and overwrite the existing directory
    for that bundle, run ``naclsdk`` with the ``--force`` option.
 
    On Mac/Linux::
 
      $ ./naclsdk update --force
 
@@ skipping 10 matching lines @@
    On Windows::
 
      > naclsdk help
 
 Next steps:
 
 * Browse through the :doc:`Release Notes <release-notes>` for important
   information about the SDK and new bundles.
 * If you're just getting started with Native Client, we recommend reading
   the :doc:`Technical Overview <../overview>` and walking through the
-  :doc:`Getting Started Tutorial </devguide/tutorial/index>`.
+  :doc:`Getting Started Tutorial </devguide/tutorial/tutorial-part1>`.
 * If you'd rather dive into information about the toolchains, see
   :doc:`Building Native Client Modules </devguide/devcycle/building>`.