Summary: Remove gists in code blocks. This also made it easier to fix the iOS sample app instructions in the getting started. >Note: I also needed to update my gems as I was having problems running `bundle install`. The errors were around installing json v1.8.3. It was resolved by creating a new Gemfile.lock. 1. Build website and check changed pages (see attached Getting Started for an example) 2. Also check how it would look for mobile site (see attached index page) Verified that the code snippets matched previous snippets and styling acceptable.   Closes https://github.com/facebook/yoga/pull/500 Differential Revision: D4834356 Pulled By: emilsjolander fbshipit-source-id: f47dca4b7518822b195f0bd5076fbf852904372b