Merge pull request codecrafters-io#59 from lotharschulz/patch-1

added 'Build your own CI server' title & one item

Author: danistefanovic

README.md

@@ -247,6 +247,7 @@
 * [**Python**: *Recommender Systems in Python: Beginner Tutorial*](https://www.datacamp.com/community/tutorials/recommender-systems-python)
 * [**Python**: *Write SMS-spam detector with Scikit-learn*](https://medium.com/@kopilov.vlad/detect-sms-spam-in-kaggle-with-scikit-learn-5f6afa7a3ca2)
 * [**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/)
 * [**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)