fix docs at the top to honor correctly expiration when used in models

Thanks @KabluBR  for spotting it

scripts/sessions2trash.py

@@ -24,7 +24,7 @@ Typical usage:
     # Delete session in a module (move to the modules folder)
     from sessions2trash import single_loop
     def delete_sessions():
-        single_loop()
+        single_loop(auth.settings.expiration)
 
 """