fix(docker): refuse root gateway runs in official image

docker-compose.yml

@@ -14,6 +14,9 @@
 #     keys; exposing it on LAN without auth is unsafe. If you want remote
 #     access, use an SSH tunnel or put it behind a reverse proxy that
 #     adds authentication — do NOT pass --insecure --host 0.0.0.0.
+#   - If you override entrypoint, keep /opt/hermes/docker/entrypoint.sh in
+#     the command chain. It drops root to the hermes user before gateway
+#     files such as gateway.lock are created.
 #   - The gateway's API server is off unless you uncomment API_SERVER_KEY
 #     and API_SERVER_HOST. See docs/user-guide/api-server.md before doing
 #     this on an internet-facing host.