[Reland] Update and expose ZeroRedundancyOptimizer docs (#53112)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/53112
Test Plan: Imported from OSS
Reviewed By: blefaudeux
Differential Revision: D26752289
Pulled By: mrshenli
fbshipit-source-id: 897257417b530e6e18788cb40c44e5cb7ac688d5
