Revert D26696938: Update and expose ZeroRedundancyOptimizer docs
Test Plan: revert-hammer
Differential Revision:
D26696938 (https://github.com/pytorch/pytorch/commit/a586c02962f614c43370fa1eede5ca0aedadafd2)
Original commit changeset: dafb00e5c9f0
fbshipit-source-id: b08604d2009f4df7b620699dd6659dfed2b02792
