Create separate documentation pages for quantization observers and fake_quants (#66125)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/66125
Before this PR, the documentation for observers and fake_quants was inlined in the
Eager mode quantization page. This was hard to discover, especially
since that page is really long, and we now have FX graph mode quantization reusing
all of this code.
This PR moves observers and fake_quants into their own documentation pages. It also
adds docstrings to all user facing module attributes such as the default observers
and fake_quants, so people can discover them from documentation without having
to inspect the source code.
For now, enables autoformatting (which means all public classes, functions, members
with docstrings will get docs). If we need to exclude something in these files from
docs in the future, we can go back to manual docs.
Test Plan:
```
cd docs
make html
python -m server.http
// inspect docs on localhost, renders correctly
```
Reviewed By: dagitses
Differential Revision: D31447613
Pulled By: vkuzo
fbshipit-source-id: 63b4cf518badfb29ede583a5c2ca823f572c8599
