docs(README): add hint for formatting on commit

README.md

@@ -23,3 +23,13 @@ Install dependencies:
 2. Open any file in `test/out` in your browser
 
 If you dont have access to the `Sitzungen` Repository, you can use the `local_test` branch
+
+## Collaboration
+
+To stay consistent in e.g. spacing and have the chance to track changes, please format the files with
+
+```
+pnpm formt
+```
+
+in the root of the repository.