Softmax added to tensor, torch and docs (#91292)
Fixes #91107
Added `softmax` docs in
- `pytorch/torch/_tensor_docs.py`
- `pytorch/torch/_torch_docs.py `
- `pytorch/docs/XXX.rst` files. Here XXX represents all those files where I made the change
Although I have added `softmax` in `docs` directory, I was not sure which files/folders required the edits so there could be issues
Pull Request resolved: https://github.com/pytorch/pytorch/pull/91292
Approved by: https://github.com/lezcano
