Backport PR #55207 on branch 2.1.x (DOC: Add whatsnew for 2.1.2) (#55221)

Backport PR #55207: DOC: Add whatsnew for 2.1.2

Co-authored-by: Thomas Li <47963215+lithomas1@users.noreply.github.com>

Author: meeseeksmachine

doc/source/whatsnew/index.rst

@@ -16,6 +16,7 @@ Version 2.1
 .. toctree::
    :maxdepth: 2
 
+   v2.1.2
    v2.1.1
    v2.1.0
 

doc/source/whatsnew/v2.1.0.rst

@@ -891,4 +891,4 @@ Other
 Contributors
 ~~~~~~~~~~~~
 
-.. contributors:: v2.0.3..v2.1.0|HEAD
+.. contributors:: v2.0.3..v2.1.0

doc/source/whatsnew/v2.1.1.rst

@@ -51,3 +51,5 @@ Other
 
 Contributors
 ~~~~~~~~~~~~
+
+.. contributors:: v2.1.0..v2.1.1|HEAD

doc/source/whatsnew/v2.1.2.rst

@@ -0,0 +1,39 @@
+.. _whatsnew_212:
+
+What's new in 2.1.2 (October ??, 2023)
+---------------------------------------
+
+These are the changes in pandas 2.1.2. See :ref:`release` for a full changelog
+including other versions of pandas.
+
+{{ header }}
+
+.. ---------------------------------------------------------------------------
+.. _whatsnew_212.regressions:
+
+Fixed regressions
+~~~~~~~~~~~~~~~~~
+-
+-
+
+.. ---------------------------------------------------------------------------
+.. _whatsnew_212.bug_fixes:
+
+Bug fixes
+~~~~~~~~~
+-
+-
+
+.. ---------------------------------------------------------------------------
+.. _whatsnew_212.other:
+
+Other
+~~~~~
+-
+-
+
+.. ---------------------------------------------------------------------------
+.. _whatsnew_212.contributors:
+
+Contributors
+~~~~~~~~~~~~