Formatting fixes:

Added empty line before heading "Information Retrieval" to fix html output.
Untabified one line in Python section.

free-programming-books.md

@@ -283,6 +283,7 @@
 * [The Architecture of Open Source Applications: Vol. 1: Elegance, Evolution, and a Few Fearless Hacks; Vol. 2: Structure, Scale, and a Few More Feerless Hacks](http://www.aosabook.org/en/index.html)
 * [The Performance of Open Source Applications](http://aosabook.org/en/)
 * [The Future of Ideas](http://the-future-of-ideas.com/download/lessig_FOI.pdf)
+
 ####Information Retrieval
 * [Introduction to Information Retrieval](http://nlp.stanford.edu/IR-book/information-retrieval-book.html)
 * [Information Retrieval: A Survey](http://www.csee.umbc.edu/csee/research/cadip/readings/IR.report.120600.book.pdf) (PDF)
@@ -1015,7 +1016,7 @@ See also [TeX](#tex)
 * [Hacking Secret Cyphers with Python](http://inventwithpython.com/hacking/chapters/) - Al Sweigart
 * [Hitchiker's Guide to Python!](http://docs.python-guide.org/en/latest/)
 * [How to Think Like a Computer Scientist: Learning with Python](http://www.greenteapress.com/thinkpython/thinkCSpy/) - Allen B. Downey, Jeff Elkner and Chris Meyers
-	* [How to Think Like a Computer Scientist: Learning with Python, Interactive Edition](http://interactivepython.org/courselib/static/thinkcspy/index.html)
+    * [How to Think Like a Computer Scientist: Learning with Python, Interactive Edition](http://interactivepython.org/courselib/static/thinkcspy/index.html)
 * [Introduction to Programming Using Python](http://python-ebook.blogspot.com) - Cody Jackson
 * [Invent Your Own Computer Games With Python](http://inventwithpython.com/chapters/) - Al Sweigart
 * [Learn Python The Hard Way](http://learnpythonthehardway.org/book/)