Description
https://pandas.pydata.org/pandas-docs/dev/reference/groupby.html
Currently we have documentation of various groupby methods on GroupBy for any methods of SeriesGroupBy and DataFrameGroupBy that share an implementation, on DataFrameGroupBy if they exist on both but do not share an implementation, or on SeriesGroupBy xor DataFrameGroupBy if they only exist on one. This can make locating the docs a bit tricky, and the documentation also contains the line:
The following methods are available in both SeriesGroupBy and DataFrameGroupBy objects, but may differ slightly, usually in that the DataFrameGroupBy version usually permits the specification of an axis argument, and often an argument indicating whether to restrict application to columns of a specific data type.
I think it would be better to generate docs for all SeriesGroupBy methods and all DataFrameGroupBy methods individually, even if they entirely overlap.
This is somewhat related to #6944, as I think it would be then possible to treat GroupBy as an internal pandas object (at least from a documentation perspective). But this isn't logically necessary.