Fix many doc issues (#37099)
Summary:
Fix https://github.com/pytorch/pytorch/issues/35643 https://github.com/pytorch/pytorch/issues/37063 https://github.com/pytorch/pytorch/issues/36307 https://github.com/pytorch/pytorch/issues/35861 https://github.com/pytorch/pytorch/issues/35299 https://github.com/pytorch/pytorch/issues/23108 https://github.com/pytorch/pytorch/issues/4661
Just a bunch of small updates on the doc.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/37099
Differential Revision: D21185713
Pulled By: albanD
fbshipit-source-id: 4ac06d6709dc0da6109a6ad3daae75667ee5863e
