Update delivery-properties.md

Explicitly calling that only JSON values of string, number or boolean are supported.

Author: jaganth

articles/event-grid/delivery-properties.md

@@ -28,7 +28,7 @@ To set headers with a fixed value, provide the name of the header and its value
 You might want to check **Is secret?** when you're providing sensitive data. The visibility of sensitive data on the Azure portal depends on the user's RBAC permission. 
 
 ## Setting dynamic header values
-You can set the value of a header based on a property in an incoming event. Use JsonPath syntax to refer to an incoming event's property value to be used as the value for a header in outgoing requests. For example, to set the value of a header named **Channel** using the value of the incoming event property **system** in the event data, configure your event subscription in the following way:
+You can set the value of a header based on a property in an incoming event. Use JsonPath syntax to refer to an incoming event's property value to be used as the value for a header in outgoing requests. Only JSON values of string, number and boolean are supported. For example, to set the value of a header named **Channel** using the value of the incoming event property **system** in the event data, configure your event subscription in the following way:
 
 :::image type="content" source="./media/delivery-properties/dynamic-header-property.png" alt-text="Delivery properties - dynamic":::