Add unsupported

Author: sethmanheim

azure-stack/operator/release-notes-security-updates.md

@@ -15,6 +15,10 @@ ms.lastreviewed: 02/19/2025
 
 This article lists all the security updates in the last three updates of Azure Stack Hub. This information is provided for reference purposes only.
 
+::: moniker range < "azs-2501"
+This version is no longer supported. For more information, see [Azure Stack Hub servicing policy](azure-stack-servicing-policy.md#keep-your-system-under-support).
+::: moniker-end
+
 ::: moniker range="azs-2501"
 ## 2501 update