Decide on license

[darribas]

We need to pick a suitable license. The previous iteration was CC-BY-SA and I'd probably lean towards something like that rather than a software based one like GPL or BSD (this is really an educational material project more than a software one). But I want to open the discussion here to document what we pick and why.

One for @pietrostefani and @darribas to decide.

[pietrostefani]

Yes agree - creative commons seems sensible to me. As it's educational material sharing and adaptation both key in my book.