DOC: updated docstrings for EX02 validation and updated code_checks
- [x] closes #51236
- [ ] [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
- [x] 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.
- [x] Added an entry in the latest `doc/source/whatsnew/vX.X.X.rst` file if fixing a bug or adding a new feature.

Closes an issue which was worked on by several people.

`./ci/code_checks.sh docstrings` is now passing completely with the `Partially validate docstrings (EX02)` section and its corresponding `--ignore_functions` list deleted and `EX02` moved to the main `Validate docstrings` command.

`pre-commit` passes on the updated files.
@MarcoGorelli I feel pretty confident about the work here except for the `What's new` description. I put it in the `2.0.0` section, is that correct? I wanted to link to the `main` function in `validate_docstrings.py`, but I couldn't find it in the documentation. I added it to the `Other enhancements` section and wasn't sure if that was correct either. Also, obviously the other contributors and I should be listed in the `What's new` section, but it appears that the `Contributors` section will be filled out later.

Sorry for all of the questions, I'm asking them because the finishing of this issue represents the work of several other people as well and I wanted to make sure that things are correct.