Add basic documentation for debugging react native apps

docs/Debugging.md

@@ -0,0 +1,20 @@
+---
+id: debugging
+title: Debugging
+layout: docs
+category: Guides
+permalink: docs/debugging.html
+next: testing
+---
+
+## Debugging React Native Apps
+To debug the javascript code of your react app do the following:
+
+ 1. Run your application in the iOS simulator.
+ 2. Press ```Command + D``` and a webpage should open up at [http://localhost:8081/debugger-ui](http://localhost:8081/debugger-ui). (Chrome only for now)
+ 3. Enable [Pause On Caught Exceptions](http://stackoverflow.com/questions/2233339/javascript-is-there-a-way-to-get-chrome-to-break-on-all-errors/17324511#17324511) for a better debugging experience.
+ 4. Press ```Command + Option + I``` to open the Chrome Developer tools, or open it via ```View``` -> ```Developer``` -> ```Developer Tools```.
+ 5. You should now be able to debug as you normally would.
+
+### Optional
+Install the [React Developer Tools](https://chrome.google.com/webstore/detail/react-developer-tools/fmkadmapgofadopljbjfkapdkoienihi?hl=en) extension for Google Chrome. This will allow you to navigate the view hierarchy if you select the ```React``` tab when the developer tools are open.

docs/NativeModulesIOS.md

@@ -4,7 +4,7 @@ title: Native Modules (iOS)
 layout: docs
 category: Guides
 permalink: docs/nativemodulesios.html
-next: testing
+next: debugging
 ---
 
 Sometimes an app needs access to platform API, and React Native doesn't have a corresponding wrapper yet. Maybe you want to reuse some existing Objective-C or C++ code without having to reimplement it in JavaScript. Or write some high performance, multi-threaded code such as image processing, network stack, database or rendering.

website/src/react-native/index.js

@@ -66,6 +66,9 @@ var App = React.createClass({
           <p>
             All operations between the JavaScript application code and the native platform are performed asynchronously, and the native modules can also make use of additional threads as well.  This means we can decode images off of the main thread, save to disk in the background, measure text and compute layouts without blocking the UI, and more.  As a result, React Native apps are naturally fluid and responsive.  The communication is also fully serializable, which allows us to leverage Chrome Developer Tools to debug the JavaScript while running the complete app, either in the simulator or on a physical device.
           </p>
+          <p>
+            See <a href="docs/debugging.html">Debugging</a>.
+          </p>
           <img src="/react-native/img/chrome_breakpoint.png" width="800" height="443" />
 
           <h2>Touch Handling</h2>