Summary:
How to load images from the Android assets folder was undocumented, and took us a little while to find out how to do it.
This is a documentation-only change.
To confirm the syntax works create a sample app with an image at `android/app/src/main/assets/foo.png`.
Then add JSX `<Image style={{width:100, height:100}} source={{uri: 'asset:/foo.png'}} />`.
See that the image is rendered (Android only).
Closes https://github.com/facebook/react-native/pull/14626
Differential Revision: D5316887
Pulled By: AaaChiuuu
fbshipit-source-id: f7d07b8b83d6460de86c1a2efac0955300cfcd78
a38f5b6b6a