Add release notes guideline to contributors guide

Signed-off-by: Sascha Grunert <sgrunert@suse.com>

contributors/guide/release-notes.md

@@ -4,7 +4,47 @@ weight: 1
 slug: "release-notes"
 ---
 
-On the kubernetes/kubernetes repository, release notes are required for any pull request with user-visible changes, such as bug-fixes, feature additions, and output format changes.
+On the kubernetes/kubernetes repository, release notes are required for any pull
+request with user-visible changes, such as bug fixes, feature additions, and
+output format changes. Release notes are one of the most important reference
+points for users about to install or upgrade to a particular release of
+Kubernetes.
+
+## Does my pull request need a release note?
+
+Any user-visible or operator-visible change qualifies for a release note. This
+could be a:
+
+- CLI change
+- API change
+- UI change
+- configuration schema change
+- behavioral change
+- change in non-functional attributes such as efficiency or availability,
+  availability of a new platform
+- a warning about a deprecation
+- fix of a previous _Known Issue_
+- fix of a vulnerability (CVE)
+
+No release notes are required for changes to:
+
+- tests
+- build infrastructure
+- fixes of bugs which have not been released
+
+## Contents of a Release Note
+
+A release note needs a clear, concise description of the change. This includes:
+
+1. an indicator if the pull request _Added_, _Changed_, _Fixed_, _Removed_,
+   _Deprecated_ functionality or changed enhancement/feature maturity (alpha,
+   beta, stable/GA)
+2. an indicator if there is user _Action required_
+3. the name of the affected API or configuration fields, CLI commands/flags or
+   enhancement/feature
+4. a link to relevant user documentation about the enhancement/feature
+
+## Applying a Release Note
 
 To meet this requirement, do one of the following:
 - Add notes in the release notes block, or