Networks: create internal docker network for proxy server

Prepare to use caddy in docker

playbook-netdata.yml

@@ -29,6 +29,8 @@
         restart_policy: "unless-stopped"
         published_ports:
           - "127.0.0.1:{{ netdata_exposed_port }}:19999"
+        networks:
+          - name: "{{ web_proxy_network }}"
         volumes:
           - "/:/host/root:ro,rslave"
           - "/etc/group:/host/etc/group:ro"