[Docs] Update torch.(squeeze, split, set_printoptions, save) docs. (#39303)
Summary:
I added the following to the docs:
1. `torch.save`.
1. Added doc for `_use_new_zipfile_serialization` argument.
2. Added a note telling that extension does not matter while saving.
3. Added an example showing the use of above argument along with `pickle_protocol=5`.
2. `torch.split`
1. Added an example showing the use of the function.
3. `torch.squeeze`
1. Added a warning for batch_size=1 case.
4. `torch.set_printoptions`
1. Changed the docs of `sci_mode` argument from
```
sci_mode: Enable (True) or disable (False) scientific notation. If
None (default) is specified, the value is defined by `_Formatter`
```
to
```
sci_mode: Enable (True) or disable (False) scientific notation. If
None (default=False) is specified, the value is defined by
`torch._tensor_str._Formatter`.
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/39303
Differential Revision: D21904504
Pulled By: zou3519
fbshipit-source-id: 92a324257d09d6bcfa0b410d4578859782b94488
