Added short description to remove_stale_contenttypes command.

django/contrib/contenttypes/management/commands/remove_stale_contenttypes.py

@@ -8,6 +8,8 @@ from django.db.models.deletion import Collector
 
 
 class Command(BaseCommand):
+    help = "Deletes stale content types in the database."
+
     def add_arguments(self, parser):
         parser.add_argument(
             "--noinput",