Documentation for divmod and rdivmod gives wrong return type
See https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.divmod.html#pandas.Series.divmod
and https://pandas.pydata.org/pandas-docs/stable/reference/api/pandas.Series.rdivmod.html#pandas.Series.rdivmod

The documentation incorrectly says that the `divmod` and `rdivmod` returns Series. However, both methods actually return 2-tuples containing two series.