As @Legoktm reported on IRC, the text in the footer
Text is available under the Creative Commons Attribution-ShareAlike License;
is missing the version, which is an important detail. This footer is meant to resemble the footer used in https://meta.wikimedia.org , and there it is linked to https://creativecommons.org/licenses/by-sa/3.0/
However, is there a way to add links to that footer? If not, we should specify the version in the text:
Text is available under the Creative Commons Attribution-ShareAlike 3.0 License;