Update README.md

Author: fsbraun

README.md

@@ -21,6 +21,7 @@ You need to have docker installed on your system to run this project.
 
 ```bash
 git clone git@github.com:django-cms/django-cms-quickstart.git
+git switch -t origin/support/cms-4.1.x
 cd django-cms-quickstart
 docker compose build web
 docker compose up -d database_default