Update u_e-dovecot-vmail-volume.md

docs/u_e-dovecot-vmail-volume.md

@@ -1,12 +1,11 @@
-If you want to use another folder for the vmail-volume, you can create an `docker-compose.override.yml` file and add:
+If you want to use another folder for the vmail-volume, you can create a `docker-compose.override.yml` file and add the following content:
+
 ```
 version: '2.1'
-volumes:
-  vmail-vol-1:
-    driver_opts:
-      type: none
-      device: /data/mailcow/vmail
-      o: bind
+services:
+    dovecot-mailcow:
+      volumes:
+        - /data/mailcow/vmail:/var/vmail
 ```
 
 ### Moving an existing vmail folder: