Adding fastpath and name parameters to docstring for Series class and others. 
- [x] closes #27178
- [x] tests added / passed
- [x] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

I modified the docstring for the Series class to include the "fastpath" and "name" parameters.  I searched the code base, and also modified the docstrings for the following classes in a similar way:

Categorial
CategoricalIndex
Grouping
Index
MultiIndex
PeriodIndex
RangeIndex

It appears that fastpath is definitely used internally, and is not deprecated.  There were no other examples of fastpath being documented in the parameters section of a docstring, so I went with this convention:

fastpath : bool, default False
        Internal use only