Fix its in FAQ
Fix its in FAQ

Summary:
When you want it to be possessive, it's just i-t-s, but when you want it to be a contraction, it's i-t-'-s.

Issue fixed: #764

- [ ] 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.
- [ ] I have reviewed the [contributing guide](https://github.com/Instagram/IGListKit/blob/master/.github/CONTRIBUTING.md)
Closes https://github.com/Instagram/IGListKit/pull/781

Differential Revision: D5129333

Pulled By: rnystrom

fbshipit-source-id: c12e15c7403f888384119c78ef632044a054c5e6

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