Update MAINTAINERS.md

Author: michaelstingl

MAINTAINERS.md

@@ -16,12 +16,12 @@ Reviewers have the ability to review PRs and approve them, but do not have merge
 - @WrenIX
 - @ferenc-hechler
 - @suse-coder
-- @kastl-ars
+- @johanneskastl / @kastl-ars
 - @Tim-herbie
 
 ## Becoming a Maintainer or Reviewer
 
 Contributors who make multiple high-quality PRs may be invited to become Reviewers.
 Reviewers who are consistently active and provide valuable reviews may be invited to become Maintainers.
 
-If you're interested in becoming a maintainer or reviewer, please continue contributing and engaging with the project.
+If you're interested in becoming a maintainer or reviewer, please continue contributing and engaging with the project.