Fix duplicate .. _references label (#2299)

* change label

* update existing whatsnew entry with new label

Author: RDaxini

docs/sphinx/source/contributing/style_guide.rst

@@ -70,7 +70,7 @@ the ``docs/readthedocs.org:pvlib-python`` link within the checks
 status box at the bottom of the pull request.
 
 
-.. _references:
+.. _reference_style:
 
 References
 ----------

docs/sphinx/source/whatsnew/v0.11.2.rst

@@ -32,7 +32,7 @@ Documentation
   :py:class:`~pvlib.pvsystem.SingleAxisTrackerMount`, and
   :py:class:`~pvlib.pvsystem.FixedMount` docstrings. Various formatting edits
   for clarity. (:issue:`1942`, :pull:`2232`)
-* Added a new citation style guide (:ref:`references`) to the contributing
+* Added a new citation style guide (:ref:`reference_style`) to the contributing
   page. (:issue:`2202`, :pull:`2226`)
 * Updated :py:func:`~pvlib.irradiance.reindl` to include definitions of terms
   and a new "notes" section (:issue:`2183`, :pull:`2193`)