Update firststeps-disable_ipv6.md

docs/firststeps-disable_ipv6.md

@@ -1,20 +1,34 @@
 This is **ONLY** recommended if you do not have an IPv6 enabled network on your host!
 
-If IPv6 MUST be disabled to fit a network, open `docker-compose.yml`, search for `enable_ipv6`...
+If you need to, you can disable the usage of IPv6 in the compose file.
+Additionally, you can  also disable the startup of container "ipv6nat-mailcow", as it's not needed if you won't use IPv6.
 
+Instead of editing docker-compose.yml directly, it is preferrable to create an override file for it 
+and implement your changes there.
+
+Go to your mailcow directory and Create a new file called "docker-compose.override.yml": 
+```
+# cd /opt/mailcow-dockerized
+# touch docker-compose.override.yml
+```
+**NOTE:** If you already have an override file, of course don't recreate it, but merge the lines below int your existing one accordingly!
+
+Open the file in your favourite text editor and fill in the following:
 
 ```
+version: '2.1'
+services:
+
+    ipv6nat-mailcow:
+      restart: "no"
+      entrypoint: ["echo", "pv6nat disabled in compose.override.yml"]
+      
 networks:
   mailcow-network:
-    [...]
+    enable_ipv6: false
-    enable_ipv6: true
-    [...]
 ```
 
-...change it to `enable_ipv6: false`.
+For these changes to be effective, you need to fully stop and then restart the stack, so containers and networks are recreated:
-
-mailcow needs to be shutdown, the containers removed and the network recreated:
-
 ```
 docker-compose down
 docker-compose up -d