Change style for license box

[libremente]

1. New line after "contenuto:"
2. When there are no restrictions, it should be cited. Something like: "Non vi sono limitazioni"
3. It could be nice to insert the icon of the license
4. The license icon should be a link to the extended page of the license, like for example https://creativecommons.org/licenses/by/4.0/deed.it.
5. Change the verbs: "Creazione" and "Distribuire" are in different form. We should pick a way to say it, I think "Creazione", "Distribuzione" etc are better