Clarify pros/cons on different navigation libraries

Summary: Closes #14292

Differential Revision: D5165551

Pulled By: hramos

fbshipit-source-id: a50c1c1eb8d4e7de619b73e1baf621dc11e00abc

docs/Navigation.md

@@ -8,11 +8,11 @@ next: images
 previous: animations
 ---
 
-This guide covers the various navigation components available in React Native. If you are just getting started with navigation, you will probably want to use [React Navigation](docs/navigation.html#react-navigation).
+This guide covers the various navigation components available in React Native. If you are just getting started with navigation, you will probably want to use [React Navigation](docs/navigation.html#react-navigation). React Navigation provides an easy to use navigation solution, with the ability to present common stack navigation and tabbed navigation patterns on both iOS and Android. As this is a JavaScript implementation, it provides the greatest amount of configurability as well as flexibility when integrating with state management libraries such as [redux](https://reactnavigation.org/docs/guides/redux).
 
-If you are only targeting iOS and would like to stick to the native look and feel, check out [NavigatorIOS](docs/navigation.html#navigatorios).
+If you're only targeting iOS, you may want to also check out [NavigatorIOS](docs/navigation.html#navigatorios) as a way of providing a native look and feel with minimal configuration, as it provides a wrapper around the native `UINavigationController` class. This component will not work on Android, however.
 
-If you're targeting both iOS and Android, the following libraries provide native navigation on both platforms: [native-navigation](http://airbnb.io/native-navigation/), [react-native-navigation](https://github.com/wix/react-native-navigation).
+If you'd like to achieve a native look and feel on both iOS and Android, or you're integrating React Native into an app that already manages navigation natively, the following libraries provide native navigation on both platforms: [native-navigation](http://airbnb.io/native-navigation/), [react-native-navigation](https://github.com/wix/react-native-navigation).
 
 ## React Navigation
 
@@ -66,7 +66,7 @@ For a complete intro to React Navigation, follow the [React Navigation Getting S
 
 ## NavigatorIOS
 
-If you are targeting iOS only, you may also want to consider using [`NavigatorIOS`](docs/navigatorios.html). It looks and feels just like [`UINavigationController`](https://developer.apple.com/library/ios/documentation/UIKit/Reference/UINavigationController_Class/), because it is actually built on top of it.
+`NavigatorIOS` looks and feels just like [`UINavigationController`](https://developer.apple.com/library/ios/documentation/UIKit/Reference/UINavigationController_Class/), because it is actually built on top of it.
 
 ![](img/NavigationStack-NavigatorIOS.gif)