Feature/beginners warning
Feature/beginners warning

Summary:
Issue fixed: #811

I don't think this change needs a item in `CHANGELOG.md` as it's not a real bug fix or enhancement that influences the behaviour of the library.

- [X] All tests pass. Demo project builds and runs.
- [ ] I added tests, an experiment, or detailed why my change isn't tested.
- [X] 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/812

Differential Revision: D5283118

Pulled By: rnystrom

fbshipit-source-id: 518d38c7f620cef3e85cae5fd4a1c48567bcc48c

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