[Docs] Minor doc fixes for init_process_group (#47644)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/47644
Minor Update to the init_process_group docs.
ghstack-source-id: 116441798
Test Plan: CI
Reviewed By: jiayisuse, mrshenli
Differential Revision: D24633432
fbshipit-source-id: fbd38dab464ee156d119f9f0b22ffd0e416c4fd7
