Update tutorial-ingestion-time-transformations-api.md

Author: guywi-ms

articles/azure-monitor/logs/tutorial-ingestion-time-transformations-api.md

@@ -27,7 +27,13 @@ In this tutorial, you learn to:
 ## Prerequisites
 To complete this tutorial, you need the following: 
 
-- Log Analytics workspace where you have at least [contributor rights](manage-access.md#manage-access-using-azure-permissions) .
+- Log Analytics workspace where you have at least [contributor rights](manage-access.md#manage-access-using-azure-permissions).
+- - A [supported Azure table](../logs/tables-feature-support) in the workspace.
+    
+    To configure this table for ingestion-time transformations, the table must already have some data.
+    
+    The table can't be linked to the workspace’s default DCR.
+
 - [Permissions to create Data Collection Rule objects](../essentials/data-collection-rule-overview.md#permissions) in the workspace.