DOC: Add section on MultiIndex.to_frame() ordering
- Closes #22662 
Hello @matthewgilbert! Thanks for submitting the PR.

 - There are no PEP8 issues in the file [`pandas/core/indexes/multi.py`](https://github.com/matthewgilbert/pandas/blob/5909f9a2313d33e4ee3c801733cc02adfb0a7a6a/pandas/core/indexes/multi.py) !

 Thanks!