Update DataPreparation.md

Updated table destination type

Day After Dashboard in a Day/DataPreparation.md

@@ -599,8 +599,8 @@ The data destination logic in Dataflows Gen2 is configured as an additional step
     | DimDate | Existing | Update |
     | DimEmployee | Existing | Update |
     | DimStore | Existing | Update |
-    | DimCustomer | Existing | Update |
+    | DimCustomer | New | Update |
-    | DimProduct | Existing | Update |
+    | DimProduct | New | Update |
 
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