Update exchange-and-refund-azure-reservations.md

Adding Defender and sentinel pre purchase plan in the list of reservations which cannot be cancelled or refunded

Author: RajeevMSFT

articles/cost-management-billing/reservations/exchange-and-refund-azure-reservations.md

@@ -39,6 +39,8 @@ Not all reservations are eligible for exchange. For example, you can't exchange
 - Synapse Analytics Pre-purchase plan
 - Red Hat plans
 - SUSE Linux plans
+- Microsoft Defender for Cloud Pre-Purchase Plan
+- Microsoft Sentinel Pre-Purchase Plan
 
 You can also refund reservations, but the sum total of all canceled reservation commitment in your billing scope (such as EA, Microsoft Customer Agreement, and Microsoft Partner Agreement) can't exceed USD 50,000 in a 12 month rolling window.
 
@@ -51,6 +53,8 @@ The following reservations aren't eligible for refunds:
 - Azure VMware solution by CloudSimple
 - Red Hat plans
 - SUSE Linux plans
+- Microsoft Defender for Cloud Pre-Purchase Plan
+- Microsoft Sentinel Pre-Purchase Plan
 
 ## Prerequisites