Update license to not be CCO

[ElenaFdR]

Because the universal footer now says it's CC0, which is definitely wrong for this repo.
@bvhme suggests:

• changing the info under current License heading on the Readme from a copyright to a trademark
• adding a license heading to every page/all content in the repo
• adding a license file to the repo, so it's extra clear this repo has a different licence from our default

Suggestions for what to put in the license file would be welcome!

[bvhme]

CC0 might be right for this repo, however we need to make clear that some things in here are trademarks as logos and audio logos etcetera and thus cannot just be reused.