Add support for batched pdist (#12302)
Summary:
This updates pdist to work for batched inputs, and updates the
documentation to reflect issues raised.
closes #9406
Pull Request resolved: https://github.com/pytorch/pytorch/pull/12302
Reviewed By: ezyang
Differential Revision: D13528485
Pulled By: erikbrinkman
fbshipit-source-id: 63d93a6e1cc95b483fb58e9ff021758b341cd4de
