Summary:
What existing problem does the pull request solve?
It fixes some formatting issues that appear in the React Native documentation.
**Test plan**
Run the documentation extraction and verify the content appears correctly as `code` formatted sections.
Closes https://github.com/facebook/react-native/pull/12346
Differential Revision: D4553340
Pulled By: hramos
fbshipit-source-id: b8307b3c3e1c3451f740c46222e10ec3c45e3008