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

Author: lotharschulz

README.md

@@ -203,6 +203,9 @@
 * [**Python**: *Building a basic HTTP Server from scratch in Python*](http://joaoventura.net/blog/2017/python-webserver/)
 * [**Ruby**: *Building a simple websockets server from scratch in Ruby*](http://blog.honeybadger.io/building-a-simple-websockets-server-from-scratch-in-ruby/)
 
+#### Build your own `CI Server`
+* [**Ruby**: *Writing a CI Server*](https://developer.github.com/v3/guides/building-a-ci-server/)
+
 #### Uncategorized
 * [**Alloy**: *The Same-Origin Policy*](http://aosabook.org/en/500L/the-same-origin-policy.html)
 * [**C**: *Building a software and hardware stack for a simple computer from scratch*](https://www.youtube.com/watch?v=ZjwvMcP3Nf0&list=PLU94OURih-CiP4WxKSMt3UcwMSDM3aTtX) [video]