Create Working with UICollectionView guide
Create Working with UICollectionView guide

Summary:
Close #527
Closes https://github.com/Instagram/IGListKit/pull/664

Differential Revision: D4906260

Pulled By: jessesquires

fbshipit-source-id: c849dd17d6161ab121d0d3dd55e59e9e0832be73

Instagram/IGListKit,zhubofei/IGListKit,Instagram/IGListKit,Instagram/IGListKit,zhubofei/IGListKit,Instagram/IGListKit,zhubofei/IGListKit,zhubofei/IGListKit,Instagram/IGListKit,zhubofei/IGListKit