Added myself

contributors.md

@@ -70,3 +70,4 @@ Thank you to all contributors:
 * [Brian Rak](https://github.com/brakthehack)
 * [Robin Peiremans](https://github.com/rpeiremans)
 * [xiaoqiang zhao](https://github.com/hitmoon)
+* [Dennis Birkholz](https://github.com/dennisbirkholz)