Open Sourcing Twelve-Factor

Well, in this specific case there is source code and it's the source to the website, which now accepts contributions rather than just being "read only." The linked article goes into why they are now open to contributions

I am not lawyerly enough to get into whether the Creative Commons are "open source" but shrug https://github.com/twelve-factor/twelve-factor/blob/main/LIC... seems to be pretty liberal with the rights offered to others