Update defender-for-storage-malware-scan.md

Add clarity around other costs related to enabling Malware Scanning

Author: yoavfr

articles/defender-for-cloud/defender-for-storage-malware-scan.md

@@ -160,6 +160,9 @@ By default, a limit of 5 TB (5,000 GB) is established if no specific capping mec
 > You can set the capping mechanism on either individual storage accounts or across an entire subscription (every storage account on the subscription will be allocated the limit defined on the subscription level).
 
 Follow [these steps](tutorial-enable-storage-plan.md#set-up-and-configure-microsoft-defender-for-storage) to configure the capping mechanism.
+## Addtional costs of malware scanning
+
+Malware scanning uses other Azure services as its foundation. This means that when you enable Malware scanning, you will also be charged for the Azure services that it requires. These services include Azure Storage read operations, Azure Storage blob indexing and Azure Event Grid notifications.
 
 ## Handling possible false positives and false negatives