Add delayed shutdown

Author: Jakobhenningjensen

docs/deployment.md

@@ -114,7 +114,7 @@ Options:
   --timeout-graceful-shutdown INTEGER
                                   Maximum number of seconds to wait for
                                   graceful shutdown.
-  --delayed-shutdown FLOAT
+  --shutdown-delay FLOAT
                                   Time in seconds to delay shutdown when a shutdown-signal is received
   --ssl-keyfile TEXT              SSL key file
   --ssl-certfile TEXT             SSL certificate file