Add Free and Open Machine Learning book to free-programming-books.md (#5009)

* Add Free and Open Machine Learning book to free-programming-books.md

* used suggested URL

Co-authored-by: Eric Hellman <eric@hellman.net>

free-programming-books.md

@@ -493,6 +493,7 @@
 * [Dive into Deep Learning](http://d2l.ai)
 * [Explorations in Parallel Distributed Processing: A Handbook of Models, Programs, and Exercises](https://web.stanford.edu/group/pdplab/pdphandbook) - James L. McClelland
 * [Foundations of Machine Learning, Second Edition](https://mitpress.ublish.com/ereader/7093/?preview=#page/Cover) - Mehryar Mohri, Afshin Rostamizadeh, Ameet Talwalkar
+* [Free and Open Machine Learning](https://freeandopenmachinelearning.readthedocs.io/en/latest/index.html) - Maikel Mardjan
 * [Gaussian Processes for Machine Learning](http://www.gaussianprocess.org/gpml/)
 * [IBM Machine Learning for Dummies](https://www.ibm.com/downloads/cas/GB8ZMQZ3) - Judith Hurwitz, Daniel Kirsch
 * [Information Theory, Inference, and Learning Algorithms](http://www.inference.phy.cam.ac.uk/itila/)