CONTRIBUTING: Drop reference to non-existing maintainer list

This project does not have this.

Reported-by: Silvano Cirujano Cuesta <silvano.cirujano-cuesta@siemens.com>
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>

CONTRIBUTING.md

@@ -40,7 +40,6 @@ Contribution Checklist
     - send patches inline, do not append them
     - no HTML emails!
     - CC people who you think should look at the patches, e.g.
-      - affected maintainers (see areas of responsibility below)
       - someone who wrote a change that is fixed or reverted by you now
       - who commented on related changes in the recent past
       - who otherwise has expertise and is interested in the topic