DOC: fix docstring for DataFrame.to_period, pandas.DataFrame.to_timestamp, pandas.DataFrame.tz_convert #58065
Fixes docstring errorrs for DataFrame and Series for methods  `pandas.DataFrame.to_period` ,`pandas.DataFrame.to_timestamp` ,`pandas.DataFrame.tz_convert`. (issue #58065)
- [ ] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [ ] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Thanks @bergnerjonas 