Bag of documentation fixes (#21846)
Summary:
Thanks henon for raising the issues.
Fixes https://github.com/pytorch/pytorch/issues/21830
Fixes https://github.com/pytorch/pytorch/issues/21831
Fixes https://github.com/pytorch/pytorch/issues/21832
Fixes https://github.com/pytorch/pytorch/issues/21827
Fixes https://github.com/pytorch/pytorch/issues/21822
Fixes https://github.com/pytorch/pytorch/issues/21820
Pull Request resolved: https://github.com/pytorch/pytorch/pull/21846
Differential Revision: D15847389
Pulled By: soumith
fbshipit-source-id: 421cc48af646a2618af731697de7d4de83d3eabe
