fix: router setup hangs on race condition with Docker.

README.md

@@ -217,7 +217,9 @@ external interface, in this order:
 Traffic from every other interface, including the internal one and the Docker bridges, is
 not affected. The rules cover IPv4 only.
 
-The `vpn-router-docker` service applies the rules after `docker.service` starts and removes
+`vpn-router-setup` starts after `docker.service`, so Docker is up when it looks for it; the
+ordering has no effect on a host without Docker. The `vpn-router-docker` service applies the
+rules after `docker.service` starts and removes
 them when Docker stops, so restarting Docker restores them. `systemctl restart
 vpn-router-setup` applies a changed configuration while Docker runs. With `docker.mode` set to
 `on`, the service fails when Docker is not installed or its daemon is not running; with