Summary:
- Make the examples runnable (both copy/paste and with the web player)
- Add a bit more information in props where needed.
Closes https://github.com/facebook/react-native/pull/8392
Differential Revision: D3482747
Pulled By: caabernathy
fbshipit-source-id: 8f2d812efc1efb3f14db45b5c054ce0d5c14f5f5