add a note about security patch

Author: haochenghuang

articles/spring-apps/enterprise/how-to-configure-planned-maintenance.md

@@ -80,6 +80,9 @@ Notifications and messages are sent out before and during the maintenance. The f
 
 Currently, Azure Spring Apps performs one regular planned maintenance to upgrade the underlying infrastructure every three months. For a detailed maintenance timeline, check the notifications on the [Azure Service Health](https://azure.microsoft.com/get-started/azure-portal/service-health) page.
 
+> [!NOTE]
+> In compliance with Microsoft’s security standards, we will perform additional security patching for underlying AKS clusters during the second week of each month. Maintenance will occur within an 8-hour window during non-working hours. This will be conducted in a rolling fashion to ensure uninterrupted service.
+
 ## Best practices
 
 - When you configure planned maintenance for multiple service instances in the same region, the maintenance takes place within the same week. For example, if maintenance for cluster A is set on Monday and cluster B on Sunday, then cluster A is maintained before cluster B, in the same week.