Track the nginx-menu playbook as it stands

It has been serving three menu Sites from an untracked directory, so today's
state was not reproducible or revertible.

nginx-menu/roles/network/tasks/main.yaml

@@ -0,0 +1,8 @@
+---
+- name: "Ensure {{ docker_container }} Docker network exists"
+  docker_network:
+    name: "{{ docker_network }}"
+    state: present
+    connected:
+      - "{{ caddy_container }}"
+    appends: yes