DOC: Improve documented types for merge
Correct list of supported types in docs
Remove block creating incorrect docs in merge

- [X] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).

xref pandas-dev/pandas-stubs#355
 This pull request is stale because it has been open for thirty days with no activity. Please [update](https://pandas.pydata.org/pandas-docs/stable/development/contributing.html#updating-your-pull-request) and respond to this comment if you're still interested in working on this. Thanks @bashtage if you could follow up with the unit test that would be great