add license

Author: wurstbrot

README.md

@@ -47,4 +47,5 @@ In this [video](https://www.youtube.com/watch?v=tX9RHZ_O5NU) Timo Pagel describe
 [![Timo Pagel IT-Consulting](https://raw.githubusercontent.com/DefectDojo/Documentation/master/doc/img/timo-pagel-logo.png)](https://pagel.pro) (Time, Logo, Icons)
 
 # License
-The OWASP DevSecOpsMaturity Model and any contributions are Copyright © by Timo Pagel 2017-2020
+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