pytorch

bee97d5b - Document the default behavior for dist.new_group() when ranks=None (#44000)

Document the default behavior for dist.new_group() when ranks=None (#44000) Summary: Pull Request resolved: https://github.com/pytorch/pytorch/pull/44000 This wasn't documented, so add a doc saying all ranks are used when ranks=None ghstack-source-id: 111206308 Test Plan: CI Reviewed By: SciPioneer Differential Revision: D23465034 fbshipit-source-id: 4c51f37ffcba3d58ffa5a0adcd5457e0c5676a5d