Amends RN for CC 20.3.0

calico-cloud_versioned_docs/version-20-2/release-notes/index.mdx

@@ -5,7 +5,7 @@ title: Release notes
 
 # Calico Cloud release notes
 
-## December 19, 2024 (version 20.3.1)
+## December 19, 2024 (version 20.3.1){#20.3.1}
 
 ### Bug fixes
 
@@ -31,6 +31,11 @@ For more information, see [Dashboards](../visibility/dashboards.mdx).
 
 ## December 3, 2024 (version 20.3.0)
 
+:::info[upgrade notice]
+Because of a breaking change, this version is no longer available.
+Upgrade instead to [Calico Cloud 20.3.1](#20.3.1) or later.
+:::
+
 ### New features and enhancements
 
 #### Image Assurance scan result management
@@ -85,6 +90,7 @@ For more information see [Deploy a dual ToR cluster](../networking/configuring/d
   When upgrading, you must ensure that existing tiers have a lower order or else policy decisions may be affected.
   For more information, see [Get started with policy tiers](../network-policy/policy-tiers/tiered-policy.mdx).
 
+
 ## November 6, 2024 (version 20.2.0)
 
 ### New features and enhancements