refactor(docs): home: write contributing

docs/unified-ticketing/contributing.md

 # Contributing
 
-!!! todo
-    - Write Basic stuff a contributor needs to full-fill & know
-    - link to the Developers Guide found in top-bar
+To contribute to this project,
+you primarily have to be a member of the University of Applied Sciences Stuttgart.  
+This project is hosted on our Transferportal's GitLab instance,
+to which only HFT members have access to my knowledge.
+
+Apart from that, for contributing to the library code itself,
+you should be able to program Java and be familiar with maven.  
+For the documentation you need to have Python installed and know how to write Markdown.
+
+For all contributions you need to use Git.
+
+For details see the [Developer Guide][dev-guide].
+There you can find information about getting ready,
+what rules to follow
+and more developers than user based documentation about the library.
+
+[dev-guide]: ../developers-guide/machine-setup.md