0a68044649
Summary: This is a first step in breaking up the getting started docs. Ultimately, the React Native Android and iOS bits will become separate sections, too, but I won't to keep the diffs a bit smaller. This one doesn't really do much apart from reorganising the current content. Reviewed By: mweststrate Differential Revision: D20815235 fbshipit-source-id: 5c85b788211699a2a9f5808b9e2590c7db68a1c1