Add tutorial codecrafters-io#95

Author: danistefanovic

README.md

@@ -303,6 +303,7 @@
 * [**Python**: _A Simple Content-Based Recommendation Engine in Python_](http://blog.untrod.com/2016/06/simple-similar-products-recommendation-engine-in-python.html)
 * [**Ruby**: _A Pedometer in the Real World_](http://aosabook.org/en/500L/a-pedometer-in-the-real-world.html)
 * [**Ruby**: _Writing a CI Server_](https://developer.github.com/v3/guides/building-a-ci-server/)
+* [**Ruby**: _Creating a Linux Desktop application with Ruby_](https://iridakos.com/tutorials/2018/01/25/creating-a-gtk-todo-application-with-ruby)
 * [**Rust**: _Let's build a browser engine_](https://limpet.net/mbrubeck/2014/08/08/toy-layout-engine-1.html)
 * [**Rust**: _Building a DNS server in Rust_](https://github.com/EmilHernvall/dnsguide/blob/master/README.md)