The content of this book might be published. Therefore we need to own the copyright for the complete content.
We might make some money from the book, but it won't be much and it is probable, that we will donate a huge amount for a good cause. The book will continue to be freely available and we'll 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 Malte Grosser and Henning Bumann".
If you have any questions, please raise them in the pull request or send an email to malte.grosser@gmail.com.