How about adding a section on the different licences available, as well as a lehman's explanation on what each licence means and how to respect them, while creating your own theme.
I say this simply because Root made a comment regarding the editiing of a Manji theme, and the specifics of it's licence agreement, therefore, this might be a good way to at least inform users without having them click on 2 or three different sites which contain a multitude of licences. For example, how does one person determine whether a GPL license is compatible with a CC licene (I think thre is a CC/GPL one too) and so on and so forth. This is still a tricky mind field for many who apply a licence not full aware of what it will cover and how it will affect the theme they are using.
Links are great, but brief surmised explanations are better, with further reading offered as a link:)