DOC: update groupby methods `See Also` section
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 https://github.com/pandas-dev/pandas/blob/e102f80c92df13fe39efbc59b53371c2cbd1d42e/pandas/core/groupby/groupby.py#L116-L122 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.