DOC: Improve documentation of kwargs for NumPy compatibility

[rhshadrach]

xref #48277

In certain locations, the API docs give very little information on kwargs that exist only for NumPy compatibility, e.g.

https://pandas.pydata.org/pandas-docs/dev/reference/api/pandas.DataFrame.sum.html

Additional keyword arguments to be passed to the function.

https://pandas.pydata.org/pandas-docs/dev/reference/api/pandas.DataFrame.clip.html

Additional keywords have no effect but might be accepted for compatibility with numpy.

This is a bit terse to me; I think it would be useful to have a section of the FAQ explaining this in a bit more detail, and to link there from appropriate docstrings.