Add Kevin as maintainer

Kevin has helped us at numerous contests for more than a year and is
still activily attending sites below the World Finals.

Partially handles: #2949

Author: vmcj

README.md

@@ -49,9 +49,9 @@ Copyright & Licensing
 
 DOMjudge is Copyright (c) 2004 - 2025 by the DOMjudge developers and
 all respective contributors. The current DOMjudge developers are Jaap
-Eldering, Nicky Gerritsen, Keith Johnson, Thijs Kinkhorst, Mart
-Pluijmaekers, Michael Vasseur and Tobias Werth; see the manual for
-a complete list of contributors.
+Eldering, Nicky Gerritsen, Kevin Jilissen, Keith Johnson, Thijs Kinkhorst,
+Mart Pluijmaekers, Michael Vasseur and Tobias Werth;
+see the manual for a complete list of contributors.
 
 DOMjudge, including its documentation, is free software; you can
 redistribute it and/or modify it under the terms of the GNU General