Add pull_policy: never to netbox services so we never try to pull locally built image from remote registry

Using-Netbox-Plugins.md

@@ -48,6 +48,7 @@ version: '3.4' # This is NOT the version of NetBox! No need to adjust :)
 services:
   netbox:
     image: netbox:latest-plugins
+    pull_policy: never
     ports:
       - 8000:8080
     build:
@@ -55,8 +56,10 @@ services:
       dockerfile: Dockerfile-Plugins
   netbox-worker:
     image: netbox:latest-plugins
+    pull_policy: never
   netbox-housekeeping:
     image: netbox:latest-plugins
+    pull_policy: never
 ```
 ## Step 3 - Enable plugins in the configuration