Correct the config path for docker-mailserver

docker-mailserver/docker-compose.yml

@@ -18,7 +18,7 @@ services:
       - mailstate:/var/mail-state
       - ./sa-learn:/etc/cron.d/sa-learn
       - maillogs:/var/log/mail
-      - config/:/tmp/docker-mailserver/
+      - config:/tmp/docker-mailserver/
       - /etc/localtime:/etc/localtime:ro
     restart: unless-stopped
     cap_add: ["NET_ADMIN", "SYS_PTRACE"]