DOC: fix SA05 errors in docstring for pandas.core.groupby.DataFrameGroupBy - first, last
- [x] xref #57392
- [x] [Tests added and passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#writing-tests) if fixing a bug or adding a new feature
- [x] All [code checks passed](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#pre-commit).
- [ ] Added [type annotations](https://pandas.pydata.org/pandas-docs/dev/development/contributing_codebase.html#type-hints) to new arguments/methods/functions.
- [ ] Added an entry in the latest doc/source/whatsnew/vX.X.X.rst file if fixing a bug or adding a new feature.

fixing SA05 errors in docstrings for:
pandas.core.groupby.DataFrameGroupBy.first
pandas.core.groupby.DataFrameGroupBy.last

> lgtm, thanks @Pistonamey

Your Welcome, so no conflicts, which means they will be merged ? Thanks @Pistonamey 