OSDOCS-12172: adds 4.16.21 relnote MicroShift

Author: ShaunaDiaz

microshift_release_notes/microshift-4-16-release-notes.adoc

@@ -333,3 +333,12 @@ Issued: 6 November 2024
 {product-title} release 4.16.20 is now available. The list of bug fixes that are included in the update is attached to the link:https://access.redhat.com/errata/RHBA-2024:8685[RHBA-2024:8685] advisory. The images that are included in the update are provided by the link:https://access.redhat.com/errata/RHSA-2024:8683[RHSA-2024:8683] advisory.
 
 See the latest images included with {microshift-short} by xref:../microshift_updating/microshift-list-update-contents.adoc#microshift-get-rpm-release-info_microshift-list-update-contents[listing the contents of the {microshift-short} RPM release package].
+
+[id="microshift-4-16-21-dp_{context}"]
+=== RHBA-2024:8988 - {microshift-short} 4.16.21 bug fix and enhancement advisory
+
+Issued: 13 November 2024
+
+{product-title} release 4.16.21 is now available. The list of bug fixes that are included in the update is attached to the link:https://access.redhat.com/errata/RHBA-2024:8988[RHBA-2024:8988] advisory. The images that are included in the update are provided by the link:https://access.redhat.com/errata/RHBA-2024:8986[RHBA-2024:8986] advisory.
+
+See the latest images included with {microshift-short} by xref:../microshift_updating/microshift-list-update-contents.adoc#microshift-get-rpm-release-info_microshift-list-update-contents[listing the contents of the {microshift-short} RPM release package].