DOC: Do no use 'type' as first word when specifying a return type (#21622)
Pycharm is otherwise confused and expects objects of type
'type' to be returned.

- [x] closes #21622 
- [x] tests added / passed (no code changes)
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x] whatsnew entry (not needed I guess)
