We treat this book-in-progress as a form of wiki. The content of this wiki will be included in a forthcoming book, and hence we need to own the copyright for the complete content of the wiki. The content of this site will continue to be freely available, and we will acknowledge all contributions in the printed book. To confirm that you’re ok with giving us your copyright, please include the phrase: "I assign the copyright of this contribution to Kenneth Benoit and Stefan Müller" in the description field of pull requests.
If you have any questions, feel free to raise them in the pull request, or contact the authors.