Add Unix as IDE repo (epub & mobi format) (#2100)

* Add Unix as IDE repo (epub & mobi format)

* Reorder alphabetically

free-programming-books.md

@@ -2148,6 +2148,7 @@ For resources on Angular, Backbone, D3, Dojo, Ember, Express, jQuery, Knockout,
 
 * [An Introduction to Unix](http://www.oliverelliott.org/article/computing/tut_unix/)
 * [Commentary on the Sixth Edition UNIX Operating System](http://www.lemis.com/grog/Documentation/Lions/) - J. Lions
+* [Unix as IDE](https://github.com/mrzool/unix-as-ide) - Tom Ryder (epub, mobi)
 * [UNIX Commands and Concepts](http://www.cs.bu.edu/teaching/unix/reference/) - Robert I. Pitts
 * [Unix for Poets](http://web.stanford.edu/class/cs124/kwc-unix-for-poets.pdf) - Kenneth Ward Church (PDF)
 * [Unix Toolbox](http://cb.vu/unixtoolbox.xhtml) - Colin Barschel