.github: Tweak the release note label message
.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 <a027184a55211cd23e3f3094f1fdc728df5e0500@cilium.io>

tklauser/cilium,tgraf/cilium,tgraf/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,tgraf/cilium,tklauser/cilium,cilium-team/cilium,tgraf/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium-team/cilium,tklauser/cilium,cilium/cilium,tgraf/cilium,tklauser/cilium,michi-covalent/cilium,michi-covalent/cilium,cilium/cilium,cilium/cilium,cilium/cilium,michi-covalent/cilium