Reorder README sections.

README.md

 Mojo
 ====
 
 Mojo is an effort to extract a common platform out of Chrome's renderer and
 plugin processes that can support multiple types of sandboxed content, such as
 HTML, Pepper, or NaCl.
 
 ## Set-up and code check-out
 
 The instructions below only need to be done once. Note that a simple "git clone"
@@ skipping 43 matching lines @@
 Bring in Android-specific build dependencies:
 ```
 $ build/install-build-deps-android.sh 
 ```
 
 Pull down all of the packages with this command:
 ```
 $ gclient sync
 ```
 
+## Update your checkout
+
+You can update your checkout like this. The order is important. You must do the
+`git pull` first because `gclient sync` is dependent on the current revision.
+
+```
+# Fetch changes from upstream and rebase the current branch on top
+$ git pull --rebase

[etiennej, 2015/11/02 13:59:39]

Rebase being optional, do we want to mention it here?

[ppi, 2015/11/02 14:09:15]

What happens when you have local changes on the branch and not pass `--rebase` -
wouldn't git then make the merge vs rebase call based on user settings? I assume
that we want to always rebase.

But I don't know really, http://xkcd.com/1597/

[etiennej, 2015/11/02 14:26:10]

Acknowledged following offline discussion.

+# Update all modules as directed by the DEPS file
+$ gclient sync
+```
+
+You do not need to rerun `gn gen out/Debug` - ninja does so automatically each
+time you build. You might need to rerun `mojo/tools/mojob.py gn` if the GN
+flags have changed.
+
 ## <a name="buildmojo"></a>Build Mojo
 
 ### Linux
 
 Build Mojo for Linux by running:
 
 ```
 $ ninja -C out/Debug -j 10
 ```
 
@@ skipping 64 matching lines @@
 ```
 $ ninja -C out/Debug -j 1000
 ```
 
 ### Official builds
 
 Official builds for android generate a signed Mojo Shell intended for
 distribution. You normally should not need to produce one. If you have any
 questions, reach out to [etiennej@chromium.org](mailto:etiennej@chromium.org).
 
-## Update your checkout
-
-You can update your checkout like this. The order is important. You must do the
-`git pull` first because `gclient sync` is dependent on the current revision.
-```
-# Fetch changes from upstream and rebase the current branch on top
-$ git pull --rebase
-# Update all modules as directed by the DEPS file
-$ gclient sync
-```
-
-You do not need to rerun `gn gen out/Debug` - ninja does so automatically each
-time you build. You might need to rerun `mojo/tools/mojob.py gn` if the GN
-flags have changed.
-
 ## Run Mojo Shell
 
 Devtools `mojo_run` is a universal shell runner abstracting away the differences
 between running on Linux and Android.
 
 Having built Mojo as described above, a demo app can be run as follows:
 
 ```
 mojo/devtools/common/mojo_run https://core.mojoapps.io/spinning_cube.mojo  # Linux
 mojo/devtools/common/mojo_run https://core.mojoapps.io/spinning_cube.mojo --android  # Android
@@ skipping 122 matching lines @@
 making your first change: [C++ in Chromium
 101](http://dev.chromium.org/developers/cpp-in-chromium-101-codelab).
 
 To land a change after receiving LGTM:
 ```
 $ git cl land
 ```
 
 Don't break the build! Waterfall is here:
 http://build.chromium.org/p/client.mojo/waterfall