Documentation Updates

[shihzy]

Hi all,

I went through the documentation. At a high level:

• Updated the main README to include the survey link
• Updated the Background-Unity to include links to Prefabs since we reference them extensively with SO Brains
• Cleaning up the Basic Guide to include screenshots and clear up the instructions from the POV of a first time user
• Minor fix in the FAQ
• Cleaned up language in the Getting Started with 3D ball
• Small typos in Imitation Learning
• Minor update to the Glossary

Let me know any comments and happy to change as needed.

Jeff

[vincentpierre]

The update of the Readme with the survey link will cause merge issues that will need to be resolved. We can cherry pick the commit to make it easier later or we can merge anyway and resolve later.