mention difference between latest and main (#13)

* mention difference between `latest` and `main`

Do a PR so drunk rabbit can complain about stuff.

* compromise between human and rabbits suggestion

Author: EvilOlaf

README.md

@@ -55,6 +55,10 @@ The port for players to connect is now **10002**.
 All server data is exposed in the `scumserver-data` folder.  
 For further information check [here](https://www.google.com/search?q=scum+server+settings).
 
+### Which Docker image? `main` or `latest`?
+
+Images tagged as `latest` are **tested and known to work.**
+Any other tag represents active development and/or automated **untested** builds.  
 
 ## Non-technical
 ### What?