DOC: Add note to mutating methods (#56877)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/56243 by adding a note to mutating functions not following the trailing `_` convention in `torch/nn/modules/module.py`
I can also raise separate PRs for other files, if needed
Pull Request resolved: https://github.com/pytorch/pytorch/pull/56877
Reviewed By: ezyang
Differential Revision: D28008856
Pulled By: jbschlosser
fbshipit-source-id: 63bfca0df05e49fceadd3167b1427dcb5542206a
