.github: Tweak the release note label message

Several first-time contributors (myself included) seem to understand the
current message as "you need to set a release note in the original post
for the bot to set a release note label". This commit tweaks the message
to try and avoid that.

Signed-off-by: Paul Chaignon <paul@cilium.io>

.github/cilium-actions.yml

@@ -39,7 +39,7 @@ require-msgs-in-commit:
 block-pr-with:
   labels-unset:
     - regex-label: "release-note/.*"
-      helper: "Release note label not set, please set the appropriate release note."
+      helper: "Please set the appropriate release note label."
       set-labels:
         - "dont-merge/needs-release-note"
   labels-set: