chore: Add missing comment on rule

Author: NickLarsenNZ

deploy/helm/opensearch-operator/templates/roles.yaml

@@ -82,6 +82,8 @@ rules:
       - list
       - patch
       - watch
+  # Required for maintaining the CRDs within the operator (including the conversion webhook info).
+  # Also for the startup condition check before the controller can run.
   - apiGroups:
       - apiextensions.k8s.io
     resources: