DOC: 15.1 release notes
RLS: v0.15.1 final
DOC: v0.15.2 whatsnew
BUG: Fix groupby methods to include *args and **kwds if applicable.
Update tutorials.rst

Add a pandas tutorial to the tutorial links.
Merge pull request #8758 from dstephens99/issue8733

BUG: Fix groupby methods to include *args and **kwds if applicable.
DOC: clean-up v0.15.1 whatsnew file
Merge pull request #8755 from jorisvandenbossche/doc-fixes2

DOC: clean-up v0.15.1 whatsnew file
Merge pull request #8759 from wavedatalab/patch-1

Update tutorials.rst
DOC: update sphinx version requirements
TST: Raise remote data error if no expiry dates are found (io.data.Options)
BUG: concat of series of dtype category converting to object dtype (GH8641)
Merge pull request #8763 from dstephens99/issue8761

TST: Raise remote data error if no expiry dates are found (Options)
Merge pull request #8714 from jreback/series_concat

BUG: concat of series of dtype category converting to object dtype (GH8641)
BLD: remove network tests from 3.2 build
BUG: fix negative step support for label-based slices

INT: make Index.slice_locs step-aware

BUG: fix PeriodIndex.searchsorted to accept Periods

INT: refactor time-related indices to use step-aware slice_locs