feature: the package installs the Router Manager, which is no longer a package of its own.

docs/docker.md

@@ -0,0 +1,11 @@
+# Docker
+
+Whether Docker is installed on the router, the state of `docker.service` and of the router's
+Docker rules, the ports exposed on the external interface, and the rules of the
+`VPN-ROUTER-DOCKER` chain.
+
+Exposed ports are set on the router as root, for example:
+
+```sh
+vpn-config-edit set --restart docker.exposed_ports 443,8000:8100
+```