Add download links for Android NDK to the docs

Summary:We don't support the latest NDK (`r11b`) and Google no longer provides links for the old version on the official page. So add them to the docs for now.

cc kmagiera astreet
Closes #6668

Differential Revision: D3102125

fb-gh-sync-id: 0a54e1c7f2ff883ca516c30cda279c828bd5a6e2
fbshipit-source-id: 0a54e1c7f2ff883ca516c30cda279c828bd5a6e2

Author: satya164

docs/AndroidBuildingFromSource.md

@@ -18,7 +18,7 @@ Make sure you have the following installed:
 1. Android SDK version 23 (compileSdkVersion in [`build.gradle`](https://github.com/facebook/react-native/blob/master/ReactAndroid/build.gradle))
 2. SDK build tools version 23.0.1 (buildToolsVersion in [`build.gradle`](https://github.com/facebook/react-native/blob/master/ReactAndroid/build.gradle))
 3. Android Support Repository >= 17 (for Android Support Library)
-4. Android NDK (download & extraction instructions [here](http://developer.android.com/ndk/downloads/index.html))
+4. Android NDK (download links and installation instructions below)
 
 Point Gradle to your Android SDK: either have `$ANDROID_SDK` and `$ANDROID_NDK ` defined, or create a local.properties file in the root of your react-native checkout with the following contents:
 
@@ -34,6 +34,14 @@ sdk.dir=/Users/your_unix_name/android-sdk-macosx
 ndk.dir=/Users/your_unix_name/android-ndk/android-ndk-r10e
 ```
 
+### Download links for Android NDK
+
+1. Mac OS (64-bit) - http://dl.google.com/android/repository/android-ndk-r10e-darwin-x86_64.zip
+2. Linux (64-bit) - http://dl.google.com/android/repository/android-ndk-r10e-linux-x86_64.zip
+3. Windows (64-bit) - http://dl.google.com/android/repository/android-ndk-r10e-windows-x86_64.zip
+4. Windows (32-bit) - http://dl.google.com/android/repository/android-ndk-r10e-windows-x86.zip
+
+You can find further instructions on the [official page](http://developer.android.com/ndk/downloads/index.html).
 
 ## Building the source