Added PyMOTW3 (#2112)

free-programming-books.md

@@ -1807,7 +1807,8 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 * [Python Idioms](http://safehammad.com/downloads/python-idioms-2014-01-16.pdf) (PDF)
 * [Python in Hydrology](http://www.greenteapress.com/pythonhydro/pythonhydro.html) - Sat Kumar Tomer
 * [Python Koans](https://github.com/gregmalcolm/python_koans) (2.7 or 3.x)
-* [Python Module of the Week](https://pymotw.com/2/)
+* [Python Module of the Week](https://pymotw.com/2/) (2.x)
+* [Python Module of the Week](https://pymotw.com/3/) (3.x)
 * [Python Practice Book](http://anandology.com/python-practice-book/index.html) (2.7.1)
 * [Python Practice Projects](http://pythonpracticeprojects.com)
 * [Python Programming](https://upload.wikimedia.org/wikipedia/commons/9/91/Python_Programming.pdf) (PDF) (2.6)