DOC: std() delta degree of freedom vs. degree of freedom

[YudiXie]

Pandas version checks

• I have checked that the issue still exists on the latest versions of the docs on main here

Location of the documentation

https://pandas.pydata.org/docs/reference/api/pandas.core.groupby.DataFrameGroupBy.std.html#pandas.core.groupby.DataFrameGroupBy.std

Documentation problem

I think the ddof parameter should mean "Delta Degrees of Freedom" instead of "Degrees of freedom", which is a bit confusing since "Degrees of freedom" = N - "Delta Degrees of Freedom"

Suggested fix for documentation

change the documentation of ddof parameter to "Delta Degrees of Freedom". Like that of the numpy documentation: https://numpy.org/doc/stable/reference/generated/numpy.std.html

[KevsterAmp]

I'd like to work on this

[KevsterAmp]

take