Add license field _somewhere_

[oscgonfer]

So, now that we are forwarding data... we should start considering adding the database license on a machine readable format.

I open it to start the discussion about whether or not we need it, which I would say it's not a bad idea, although I am not sure where to add it to. A proposal, would be to have a license field on devices or somewhere else with:

• name: str
• description: str
• definition: str (basically the url)