[1.7.x] Document -l as well as --list on migrate

docs/ref/django-admin.txt

@@ -698,7 +698,7 @@ be warned that using ``--fake`` runs the risk of putting the migration state
 table into a state where manual recovery will be needed to make migrations
 run correctly.
 
-.. django-admin-option:: --list
+.. django-admin-option:: --list, -l
 
 The ``--list`` option will list all of the apps Django knows about, the
 migrations available for each app and if they are applied or not (marked by