Add provisional note on license for contributions

Change-Id: Ia86cb029fe69322ea30cb76aabcc1a7a3b742cb6
diff --git a/Readme.md b/Readme.md
index 4b41317..b753a96 100644
--- a/Readme.md
+++ b/Readme.md
@@ -137,6 +137,9 @@
   $ mvn java-formatter:format
 ```
 
+Please note that unless you explicitly state otherwise any
+contribution intentionally submitted for inclusion into Krill shall –
+as Krill itself – be under the [BSD-2 License](https://raw.githubusercontent.com/KorAP/Krill/master/LICENSE).
 
 ## References