Summary:This really stumped me and I thought it could be added to the docs.
Closes https://github.com/facebook/react-native/pull/6136
Differential Revision: D2973912
Pulled By: mkonicek
fb-gh-sync-id: 0da1a946e2c2ad00056037a6492be3e99096582e
shipit-source-id: 0da1a946e2c2ad00056037a6492be3e99096582e