add license infos

Author: wurstbrot

README.md

@@ -56,3 +56,6 @@ You are using the model or you are inspired by it, want to help but don't want t
 # License
 This program is free software: you can redistribute it and/or modify it under the terms of the [GPL 3](https://www.gnu.org/licenses/) license.
 The OWASP DevSecOps Maturity Model and any contributions are Copyright © by Timo Pagel 2017-2020
+The intellectual property (content in the _data_ folder) is licensed under Attribution-ShareAlike.
+An example attribution by changing the content:
+> This work is based on the [OWASP DevSecOps Maturity Model](https://dsomm.timo-pagel.de).