validate_docstrings.py as a separate package?
The docstring validation script is quite nice! I would like to use it for instance to validate docsting in scikit-learn, e.g. 
```
python pandas/scripts/validate_docstrings.py sklearn.linear_model.LinearRegression
```
works, but then is a bit more difficult to customize being pandas specific.
In particular it would be nice to have the ability to specify which error to include / exclude in some config file. Also for instance scikit-learn has some default configuration for doctests that is currently ignored in `setup.cfg`,
```
[tool:pytest]
doctest_optionflags = NORMALIZE_WHITESPACE ELLIPSIS
```

Overall, it would be nice if this script was a separate project with a shared core functionality and possibly some config that that projects could personalize a bit if needed (although going with the 'black' approach with one set of rules for all is also a possibility).

Docstring validation is a problem that is relevant for a number of scientific python projects and it would be a shame if each one solves it independently. As far as I can tell, so far this script provides more relevant errors for scientific python projects that say `pydocstyle`. Using the same tool for validation, would also help making docstrings formatting more consistent across projects.

 Also this script is bound to grow in scope (e.g. https://github.com/pandas-dev/pandas/issues/28701) and eventually sharing the maintenance with maintainers of other projects might be useful. Although I agree that it might add some overhead with respect to your CI integration.  