Formatting changes for gradient scaling (#33832)
Summary:
hard to get right locally...I can build the docs but never quite match what it looks like live. the bullet point indentation was just an oversight.
Removing `Returns:` formatting tabs because they take up a lot of space when rendered and add no clarity. Some functions in Pytorch [do use them](https://pytorch.org/docs/master/torch.html#torch.eye), but [many don't bother](https://pytorch.org/docs/master/torch.html#torch.is_tensor), so apparently some people shared my feelings (Not using them is in line with existing practice).
Pull Request resolved: https://github.com/pytorch/pytorch/pull/33832
Differential Revision: D20135581
Pulled By: ngimel
fbshipit-source-id: bc788a7e57b142f95c4fa5baf3fe01f94c45abd8
