Merge pull request #1337 from jbranchaud/add-modern-c-book

Add a link to Modern C book (as pdf).

free-programming-books.md

@@ -726,6 +726,7 @@ Original Source: [Free Programming books](http://stackoverflow.com/revisions/392
 * [Deep C](http://www.slideshare.net/olvemaudal/deep-c)
 * [Essential C](http://cslibrary.stanford.edu/101/EssentialC.pdf) (PDF)
 * [Learn C the hard way](http://c.learncodethehardway.org/book/)
+* [Modern C](http://icube-icps.unistra.fr/img_auth.php/d/db/ModernC.pdf) (PDF)
 * [Object Oriented Programming in C](http://www.planetpdf.com/codecuts/pdfs/ooc.pdf) (PDF)
 * [The C book](http://publications.gbdirect.co.uk/c_book/)
 * [The Craft of Text Editing or A Cookbook for an Emacs](http://www.finseth.com/craft/) - Craig A. Finseth