Added Codecademy description

Elaborated on the Codecademy description so it specifies that the user's code is interpreted in-browser for feedback on the user's work. This part wasn't specified very well in the previous description.

Author: Steven Bock

docs/intro/learning.rst

@@ -30,7 +30,7 @@ If you want a more traditional book, *Python For You and Me* is an excellent
 resource for learning all aspects of the language.
 
     `Python for You and Me <http://pymbook.readthedocs.org/>`_
-
+    
 Online Python Tutor
 ~~~~~~~~~~~~~~~~~~~
 
@@ -143,6 +143,7 @@ Learn to Program in Python with Codeacademy
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 A Codeacademy course for the absolute Python beginner. This free and interactive course provides and teaches the basics (and beyond) of Python programming whilst testing the user's knowledge in between progress.
+This course also features a built in interpreter for receiving instant feedback on your learning.
 
     `Learn to Program in Python with Codeacademy <http://www.codecademy.com/en/tracks/python>`_