Add release-notes because check-prow-config fails

Signed-off-by: Enrico La Cava <enrico.lacava@flex.ai>

Author: lerrigatto

github/ci/prow-deploy/kustom/base/configs/current/plugins/plugins.yaml

@@ -105,6 +105,7 @@ plugins:
     - approve
     - lgtm
     - trigger
+    - release-note
 
   kubevirt/cloud-image-builder:
     plugins: