add changelog section

CONTRIBUTING.md

@@ -75,6 +75,12 @@ private EntityUid Slice(...)
 }
 ```
 
+# Changelogs
+
+By default any changelogs goes in the DeltaV changelog, you can use the DeltaV admin changelog by putting `DELTAVADMIN:` in a line after `:cl:`.
+
+Do not use `ADMIN:` as **it will mangle** the upstream admin changelog!
+
 # Additional resources
 
 If you are new to contributing to SS14 in general, have a look at the [SS14 docs](https://docs.spacestation14.io/) or ask for help in `#contribution-help` on [Discord](https://go.delta-v.org/AtDxv)!