[FX] Minor docs changes (#50966)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/50966
Test Plan: Imported from OSS
Reviewed By: suo
Differential Revision: D26029101
Pulled By: jamesr66a
fbshipit-source-id: 4374771be74d0a4d05fdd29107be5357130c2a76
