Fix a typo.

templates/haproxy-docker-stack.yml.j2

@@ -35,10 +35,10 @@ services:
 {% endif %}
     networks:
 {% for overlay_net in haproxy_docker_overlay_default_network %}
-      - {{ overlay_net }}:
+      - {{ overlay_net }}
 {% endfor %}
 {% for add_overlay_net in haproxy_docker_swarm_overlay_additional_networks %}       
-      - {{ add_overlay_net }}:
+      - {{ add_overlay_net }}
 {% endfor %}
     ports:
       - target: {{ haproxy_default_port }}