Add external tutorial

Running Community Solid Server with Debian, pm2, and nginx
https://github.com/mrkvon/css-setup

Related to #8

Author: mrkvon

README.md

@@ -5,3 +5,4 @@ Tutorials related to the Community Solid Server
  * [Modifying existing Components.js configurations](custom-configurations.md)
  * [An example repository of an external component](https://github.com/CommunitySolidServer/hello-world-component)
  * [A tool to generate custom configurations](https://communitysolidserver.github.io/configuration-generator/)
+ * [Production setup tutorial with Debian, pm2, and nginx](https://github.com/mrkvon/css-setup)