Add documentation for torch.overrides submodule. (#48170)
Summary:
Fixes https://github.com/pytorch/pytorch/issues/48087
Pull Request resolved: https://github.com/pytorch/pytorch/pull/48170
Reviewed By: ejguan
Differential Revision: D25220942
Pulled By: ezyang
fbshipit-source-id: a2b7f7b565f5e77173d8ce2fe9676a8131f929b6
