Add licensing info in README.md

[ghost]

No description provided.

[ghost]

@mikepan, maybe you will agreed use CC0 1.0 license for this book?

• https://creativecommons.org/publicdomain/zero/1.0/

[torvn77]

No, better use CC BY-SA https://creativecommons.org/licenses/by-sa/4.0/

Long live freedom!

[mikepan]

I think CC BY-SA works for me. One key issue is that we might want to publish the book on a different platform (possibly BlenderCloud). I want to make sure everyone who contributed to this repo is okay with it.

[ghost]

@mikepan, please, add what version of the CC BY-SA license you mean and add link to text of this license in README.md :

• CC BY-SA 3.0 - http://creativecommons.org/licenses/by-sa/3.0/
• CC BY-SA 4.0 - http://creativecommons.org/licenses/by-sa/4.0/