Co-authored-by: Guy Carmeli <guyca@users.noreply.github.com>

What's changed:
- Added a new side bar, `Third party integration` and to that added `React Context API` and `MobX` documentation. 
- Added a limitation of using React Context API with RNN so people are informed of such caveat.
- Informed the readers that if they wish to trigger re-renders across all screens, they need to use the alternatives such as MobX or Redux.