Add demo

[andreareginato]

We need to add the link to the demo and to the source code of it. As far as we have a similar goal for lelylan-ng, device-directive-ng and the dashboard, we can link the source code for the final dashboard and we can also make a full article, maybe in the blog or in the lab, describing the usage of:

• usage of lelylan-ng
• usage of lelylan-directive-ng
• usage of the dashboard