I saw several small issues with the licenses proposed for wikis:
* there is a new GFDL version, 1.3;
* there is a CC0 International “license” that has the same effects as CC publicdomain, without being based on the US law;
* there are official CC buttons that are slightly different from the ones on DokuWiki, in the same style.
Here is a git-formated patch proposal that answers to all these issues.