Add warning about sum aggregation

Author: pkshultz

articles/batch/batch-diagnostics.md

@@ -45,6 +45,11 @@ To view all Batch account metrics:
 3. Select one or more of the metrics. If you want, select additional resource metrics by using the **Subscriptions**, **Resource group**, **Resource type**, and **Resource** dropdowns.
     * For count-based metrics (like "Dedicated Core Count" or "Low-Priority Node Count"), use the "Average" aggregation. For event-based metrics (like "Pool Resize Complete Events"), use the "Count" aggregation.
 
+> [!WARNING]
+> Do not use the "Sum" aggregation, which adds up the values of all data points received over the period of the chart
+> 
+> 
+
     ![Batch metrics](media/batch-diagnostics/metrics-portal.png)
 
 To retrieve metrics programmatically, use the Azure Monitor APIs. For example, see [Retrieve Azure Monitor metrics with .NET](https://azure.microsoft.com/resources/samples/monitor-dotnet-metrics-api/).