[doc] :class: hunt
part 2 Doc clean up continued from https://github.com/huggingface/transformers/pull/14954

- `:meth:`, `:func` - all is good
- `:class:`

```
find . -type d -name ".git" -prune -o -type f -exec perl -pi -e 's#:class: ?`([^`]+)`#[`$1`]#g' {} \;
find . -type d -name ".git" -prune -o -type f -exec perl -pi -e 's#:class: ?\*([^\*]+)\*#[`$1`]#g' {} \;
git checkout examples utils/check_repo.py
```

let me know if there are any other left-over rst tags to hunt down.

@sgugger 
