Updates rounding_mode documentation to remove "true" (#52202)
Summary:
In design review the use of the word "true" for a "rounding mode" which actually performed no rounding was, understandably, considered confusing. This PR updates the documentation to remove references to "true." The signatures for torch.div and torch.divide are updated to reflect the future behavior where rounding_mode=None will be the default.
This is slightly inaccurate. Today when rounding mode is not specified it is effectively None, but users cannot actually specify rounding_mode=None today. That change was considered too disruptive to the 1.8 branch cut process.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/52202
Reviewed By: gchanan
Differential Revision: D26424979
Pulled By: mruberry
fbshipit-source-id: db3cc769c0d9c6d7e42bfad294073c99fa9168d9
