Refactored rpc docs (#35109)
Summary:
Reorganize as per jlin27 's comments. Screenshots added in comments.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/35109
Differential Revision: D20788774
Pulled By: rohan-varma
fbshipit-source-id: 7d64be70ef76ed6ff303d05d39c338293c234766
