added Elixir book (#2956)

free-programming-books.md

@@ -1091,6 +1091,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [Getting Started Guide](http://elixir-lang.org/getting-started/introduction.html) (HTML) [(PDF, MOBI, EPUB)](https://github.com/potatogopher/elixir-getting-started)
 * [Joy of Elixir](https://joyofelixir.com) - Ryan Bigg (HTML) - [Source](https://github.com/radar/joyofelixir) (:construction: *in process*)
 * [Learning Elixir](http://learningelixir.joekain.com) - Joseph Kain Blog (HTML)
+* [The Ultimate Guide To Elixir For Object-Oriented Programmers](http://www.binarywebpark.com/ultimate-guide-elixir-object-oriented-programmers) - Bruce Park (HTML)
 
 
 #### Ecto