fix url 404

Author: awong1900

README.md

@@ -23,7 +23,7 @@ yarn install
 
 Click the run button in Xcode, if something went wrong, you need to rebuild all packages that be used in this project with Xcode (Just select the package and press **command+B** to run compile).
 
-If you want to run it on your iPhone, please follow the [Offical Doc](http://facebook.github.io/react-native/docs/runningondevice.html#content).
+If you want to run it on your iPhone, please follow the [Offical Doc](http://facebook.github.io/react-native/docs/running-on-device).
 
 If you want to run it on your Android, please run:
 ```