Revert D34154832: [pytorch][PR] Add `multi_head_attention_forward` to functional rst docs
Test Plan: revert-hammer
Differential Revision:
D34154832 (https://github.com/pytorch/pytorch/commit/bafaf0d610087259f6aabf3a01bd43539651e159)
Original commit changeset: 7279d05f31d4
Original Phabricator Diff: D34154832 (https://github.com/pytorch/pytorch/commit/bafaf0d610087259f6aabf3a01bd43539651e159)
fbshipit-source-id: fcbc896b25f3b51a7ce0c5dc1dca652f57f7218c
(cherry picked from commit afa53acdfd752a844d9ec2a26d6b61a170c8b51a)
