Fix GitHub capitalization
Fix GitHub capitalization

Summary:
Issue fixed: --

- [x] All tests pass. Demo project builds and runs.
- [ ] I added tests, an experiment, or detailed why my change isn't tested.
- [ ] I added an entry to the `CHANGELOG.md` for any breaking changes, enhancements, or bug fixes.
- [x] I have reviewed the [contributing guide](https://github.com/Instagram/IGListKit/blob/master/.github/CONTRIBUTING.md)
Closes https://github.com/Instagram/IGListKit/pull/666

Differential Revision: D4906205

Pulled By: jessesquires

fbshipit-source-id: b24e187dcc16fda2305804add4129da60197e86c

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