Update Build and Running documentation.

blimp/docs/build.md

+[TOC]
+
+# Checkout
+If you want to build the Android client then you would need to follow

[Kevin M, 2016/06/28 22:31:52]

will need

[Sriram, 2016/06/28 23:22:38]

Done.

+instruciton [here](https://www.chromium.org/developers/how-tos/android-build-instructions)

[Kevin M, 2016/06/28 22:31:52]

typo: "instructions"

[Sriram, 2016/06/28 23:22:38]

Done.

+to sync Android related code as well.
+
 # Using GN
 Blimp only supports building using [GN](../../tools/gn/README.md). A quick
 overview over how to use GN can be found in the GN
 [quick start guide](../../tools/gn/docs/quick_start.md).
 
 ## Building
 
 There are two different build configurations depending on what you want to
 build:
 
@@ skipping 27 matching lines @@
 ninja -C out-android/Debug blimp && \
     out-android/Debug/bin/install_blimp_apk_incremental
 ```
 
 To add your own build preferences:
 
 ```bash
 gn args out-android/Debug
 ```
 
+For example, you can build `x86` APK by adding `target_cpu = "x86"` to the `gn
+args`.
+
+
 ### Engine
 
 Create another out-directory and set the GN args:
 
 ```bash
 mkdir -p out-linux/Debug
 echo "import(\"//build/args/blimp_engine.gn\")" > out-linux/Debug/args.gn
 gn gen out-linux/Debug
 ```
 
@@ skipping 22 matching lines @@
 (non-default for Chrome) behavior desired by Blimp (see below).
 
 ## Updating bulid arguments in templates
 
 Build argument templates exist for the client and engine at
 [`build/args/blimp_client.gn`](../../build/args/blimp_client.gn) and
 [`build/args/blimp_engine.gn`](../../build/args/blimp_engine.gn).
 
 These can be updated as in the same manner as your personal `args.gn` files
 to override default argument values.