Add missing docstrings to public methods in cacheprovider.py (lines 478-586) #13625
Description
When I was looking at the src/_pytest/cacheprovider.py file, I noticed that there are some missing docstrings. Some public methods and pytest hook functions don't have docstrings but similar methods in the same file have documentation. I propose adding docstrings to lines 478 to 586, specifically to pytest_addoption(), pytest_configure(), and cacheshow(). I can submit a PR for this if you agree.