Split iOS and Android docs into different categories

docs/NativeModulesIOS.md

@@ -1,10 +1,10 @@
 ---
 id: native-modules-ios
-title: Native Modules (iOS)
+title: Native Modules
 layout: docs
-category: Guides
+category: Guides (iOS)
 permalink: docs/native-modules-ios.html
-next: native-modules-android
+next: native-components-ios
 ---
 
 Sometimes an app needs access to platform API, and React Native doesn't have a corresponding module yet. Maybe you want to reuse some existing Objective-C, Swift or C++ code without having to reimplement it in JavaScript, or write some high performance, multi-threaded code such as for image processing, a database, or any number of advanced extensions.
@@ -264,7 +264,7 @@ You can then define methods and export your enum constants like this:
             @"statusBarAnimationFade" : @(UIStatusBarAnimationFade),
             @"statusBarAnimationSlide" : @(UIStatusBarAnimationSlide) }
 };
-    
+
 RCT_EXPORT_METHOD(updateStatusBarAnimation:(UIStatusBarAnimation)animation
                                 completion:(RCTResponseSenderBlock)callback)
 ```