DOC: Update cheat sheet and create link in docs (#20366)

* DOC: Update cheat sheet and create link in docs

* updated link to cheat sheet

Author: Dr-Irv

doc/cheatsheet/Pandas_Cheat_Sheet.pdf

@@ -13,6 +13,8 @@ pandas' own :ref:`10 Minutes to pandas<10min>`.
 
 More complex recipes are in the :ref:`Cookbook<cookbook>`.
 
+A handy pandas `cheat sheet <http://pandas.pydata.org/Pandas_Cheat_Sheet.pdf>`_.
+
 pandas Cookbook
 ---------------