Add Jorrit Siebelink as a backer - thank you! :)

Author: bryphe

BACKERS.md

@@ -134,6 +134,7 @@ Thanks you to all our backers for making Oni possible!
 *   Thomas Frick
 *   LinuxLefty
 *   Leon Bogaert
+*   Jorrit Siebelink
 
 <a href="https://opencollective.com/oni/tiers/backer/0/website" target="_blank"><img src="https://opencollective.com/oni/tiers/backer/0/avatar.png"></a>
 <a href="https://opencollective.com/oni/tiers/backer/1/website" target="_blank"><img src="https://opencollective.com/oni/tiers/backer/1/avatar.png"></a>