[docs] Transformer: no batch dim support doc update (#70597)
Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/70597
Reviewed By: VitalyFedyunin
Differential Revision: D33405284
Pulled By: jbschlosser
fbshipit-source-id: 04f37e8b9798ded7fcedac48629645843a0e3a28
