Add fonts' and icons' licenses to LICENSE

After merging #57 (closed) we now have the fonts and icons we use self-hosted and should therefore add their licenses to our LICENSE file.

added Doing Q1 labels

assigned to @gk

removed Q1 label

added Q2 label

added Documentation label

added 40m of time spent

mentioned in merge request !66 (merged)

closed with merge request !66 (merged)