Summary:
Currently in the documentation is not clear on how to use the `openDrawer` and `closeDrawer` methods. There is no mention of the requirement to use refs in order to access the Drawer. This should make it clear on how to do the above.
Closes https://github.com/facebook/react-native/pull/13961
Differential Revision: D5479993
Pulled By: hramos
fbshipit-source-id: 4d29f695fbaf097d47f75b345b9998f61156f467