chore: drop container labels from cadvisor, require webtop CUSTOM_USER, trim env template comments

webtop/compose.yml

@@ -4,7 +4,7 @@ services:
     restart: unless-stopped
     shm_size: 1gb
     environment:
-      - CUSTOM_USER=${CUSTOM_USER:-miti99}
+      - CUSTOM_USER=${CUSTOM_USER:?required}
       - PASSWORD=${PASSWORD:?required}
       - PUID=1000
       - PGID=1000