ENH Adds test and docs for dropout for no batch dims (#61911)
Summary:
Towards https://github.com/pytorch/pytorch/issues/60585
I think `Dropout` is already tested in `test_Dropout` for no batch dims.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/61911
Reviewed By: albanD
Differential Revision: D29810928
Pulled By: jbschlosser
fbshipit-source-id: 7716a1a808e9e34aae43573f38706212552afbb4
