Format note according to the Style Guide

Author: hector12free

docs/intro/learning.rst

@@ -209,7 +209,7 @@ in Python. Magic methods are surrounded by double underscores (i.e. __init__)
 and can make classes and objects behave in different and magical ways.
 
     `A Guide to Python's Magic Methods <http://www.rafekettler.com/magicmethods.html>`_
-Note: The Rafekettler.com is currently down, you can go to their Github version directly. Here you can find a PDF version:
+.. note:: The Rafekettler.com is currently down, you can go to their Github version directly. Here you can find a PDF version:
     `A Guide to Python's Magic Methods (repo on GitHub) <https://github.com/RafeKettler/magicmethods/blob/master/magicmethods.pdf>`_