DOC: docstring validation script improvements
Based on the experience from the sprint, some known issues:

- [X] args, kwargs (or kwds) issue (fixed in #20061)
- [X] no punctuation needed at end of explanation it last line is a `versionadded` (#22405)
- [ ] not working for some methods that are not imported in pandas like `pandas.core.resample.Resampler.backfill`
- [ ] parameter description starting with bullet point (starting with capital letter error)
- [ ] parameter description containing bullet points at the end (missing ending period error) (#25461)
- [ ] define standard for lists in parameters, enforce the format, and remove error that description needs to end with a period when there is a list
- [ ] handle newlines in docstring text (eg in parameter description)
- [x] verify order of the sections (e.g. `See Also` before `Examples`...) (#23133)
- [x] verify that `pandas` and `numpy` are not being imported (#23134)
- [ ] verify that there is no blank line after the title sections
- [x] `See Also` items do not start with `pandas.` (#23136)
- [x] Using `string`, `boolean`, `integer` in the param descriptions (should be `str`, `bool`, `int`) (#23165)
- [x]  `Returns` section: first line with type only if a single return, desc starting with capital and ending with period... (#23138)
- [x] flake8 examples (#23154)
- [ ] `axis` parameter using the same format `{0 or 'index', 1 or 'columns'}`
- [ ] add validations from decisions made in #20309 (quotes to use...)
- [ ] decide whether to use `NaN`, `nan`, `NA`... and warn if the others are found
- [ ] define standard on when to use backticks (single or double) and quotes, and verify common cases (like `None`, `NaN`...)
- [x] Decription of items in `See Also` starts with capital letter and ends with period. (#23135)

cc @TomAugspurger @datapythonista @WillAyd others that you noticed?