DOC: update groupby methods `See Also` section

[mzeitlin11]

Right now the default See Also section for a groupby method will include Series.groupby and DataFrame.groupby, both of which do not link to anything (and are not particularly informative on their own without a link). See for example https://pandas.pydata.org/docs/reference/api/pandas.core.groupby.GroupBy.all.html.

Based on

pandas/pandas/core/groupby/groupby.py

Lines 116 to 122 in e102f80

	_common_see_also = """
	See Also
	--------
	Series.%(name)s : Apply a function %(name)s to a Series.
	DataFrame.%(name)s : Apply a function %(name)s
	to each row or column of a DataFrame.
	"""

seems like the expected See Also would be to instead (for example with method all) link to
Series.all and DataFrame.all? The See Also could still link to groupby material if thought helpful, eg https://pandas.pydata.org/docs/reference/api/pandas.Series.groupby.html#pandas.Series.groupby and https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.groupby.html#pandas.DataFrame.groupby, but IMO most important is linking to the analogous Series/DataFrame doc which will usually be more informative.

Some groupby methods like backfill and quantile (https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.core.groupby.DataFrameGroupBy.quantile.html) do include custom See Also sections, but Series.quantile and DataFrame.quantile do not render as links.

[rhshadrach]

Agree that the Series/DataFrame versions are more informative. +0 on removing the links to Series.groupby and DataFrame.groupby.

[debnathshoham]

I am interested in looking into why those links are not rendered.
But I was not able to find anything on my own, could you please suggest where I should be looking at?