OSDOCS-15948: RN for for enabling token-based authentication on an existing AWS cluster

Author: sslocket

release_notes/ocp-4-20-release-notes.adoc

@@ -854,6 +854,13 @@ To manage the default or custom catalog sources, you still interact with Operato
 [id="ocp-release-notes-postinstallation-configuration_{context}"]
 === Postinstallation configuration
 
+[id="ocp-release-notes-enabling-sts-existing-cluster_{context}"]
+==== Enabling {aws-full} {sts-first} on an existing cluster
+
+With this release, you can configure your {aws-short} {product-title} cluster to use {sts-short} even if you did not do so during installation.
+
+For more information, see xref:../post_installation_configuration/changing-cloud-credentials-configuration.adoc#enabling-aws-sts-existing-cluster_changing-cloud-credentials-configuration[Enabling AWS Security Token Service (STS) on an existing cluster].
+
 [id="ocp-release-notes-rhcos_{context}"]
 === {op-system-first}