More fixes to the build instructions.

docs/ios_build_instructions.md

-# iOS Build Instructions
+# Checking out and building Chromium for iOS
 
+There are instructions for other platforms linked from the 
+[get the code](get_the_code.md) page.
+
 **See also [the old version of this page](old_ios_build_instructions.md).**
 
+## Instructions for Google Employees
+
+Are you a Google employee? See
+[go/building-chrome](https://goto.google.com/building-chrome) instead.
 Google employee? See [go/building-chrome](https://goto.google.com/building-chrome) instead.
 
 [TOC]
 
 ## System requirements
 
 * A 64-bit Mac running 10.11+.
 * [Xcode](https://developer.apple.com/xcode) 8.0+.
 * The OS X 10.10 SDK. Run
 
@@ skipping 79 matching lines @@
 ```
 
 Note: you need to run `setup-gn.py` script every time one of the `BUILD.gn`
 file is updated (either by you or after rebasing). If you forget to run it,
 the list of targets and files in the Xcode solution may be stale.
 
 You can also follow the manual instructions on the 
 [Mac page](mac_build_instructions.md), but make sure you set the
 GN arg `target_os="ios"`.
 
-## Running
+## Running `ios_web_shell`
 
 Any target that is built and runs on the bots (see [below](#Troubleshooting))
 should run successfully in a local build. As of the time of writing, this is
 only the `ios_web_shell` and `ios_chrome_unittests` targets—see the note at the
 top of this page. Check the bots periodically for updates; more targets (new
 components) will come on line over time.
 
 To run in the simulator from the command line, you can use `iossim`. For
 example, to run a debug build of `ios_web_shell`:
 
@@ skipping 72 matching lines @@
 
 ```shell
 $ xcodebuild -license
 ```
 
 Only accepting for all users of the machine requires root:
 
 ```shell
 $ sudo xcodebuild -license
 ```