Improve docs for scatter and gather functions (#49679)
Summary:
- Add warning about non-unique indices
- And note that these functions don't broadcast
- Add missing `torch.scatter` and `torch.scatter_add` doc entries
- Fix parameter descriptions
- Improve code examples to make indexing behaviour easier to understand
Closes gh-48214
Closes gh-26191
Closes gh-37130
Closes gh-34062
xref gh-31776
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49679
Reviewed By: mruberry
Differential Revision: D25693660
Pulled By: ngimel
fbshipit-source-id: 4983e7b4efcbdf1ab9f04e58973b4f983e8e43a4
