Summary: Move the code to the github folder, add more docs and improve the example.
We might want to merge this with `LinkingIOS` later (it has the same functionality
plus support for deep links) but want to see how people use the `IntentAndroid`
API first (and what other methods we should add) to have more data points.
public
Reviewed By: lexs
Differential Revision: D2646936
fb-gh-sync-id: 751f35784d387efcd031f9b458821cdfde048a54
Martin Konicek