Added some details about:
- `pip uninstall functorch` being helpful if there are problems
- `pip install functorch` still working for BC reasons.
Test Plan:
- wait for docs preview
Pull Request resolved: https://github.com/pytorch/pytorch/pull/86823
Approved by: https://github.com/samdow
I modified the docs website:
- It has a new install page which we'll fill out l ater
- It has a new "whirlwind tour" section with is just our README
copy-pasted
- It has a "UX Limitations" section describing arbitrary python
mutation, in-place operations, and control flow.
Please let me know if you think anything else should be here.
Future work:
- I'm going to put up a table of what operators we have support for and
which ones we don't, autogenerated via OpInfo
