Update vpn-gateway-howto-setup-alerts-virtual-network-gateway-log.md

Author: anzaman

articles/vpn-gateway/vpn-gateway-howto-setup-alerts-virtual-network-gateway-log.md

@@ -52,6 +52,10 @@ The following example steps will create an alert for a disconnection event that
 6. Fill in the details, and ensure that **Send to Log Analytics** and **TunnelDiagnosticLog** are selected. Choose the Log Analytics Workspace that you created in step 3.
 
    ![Selected check boxes](./media/vpn-gateway-howto-setup-alerts-virtual-network-gateway-log/log-alert5.png  "Select")
+   
+> [!NOTE]
+> It may take a few hours for the data to show up initially.
+>
 
 7. Go to the overview for the virtual network gateway resource and select **Alerts** from the **Monitoring** tab. Then create a new alert rule or edit an existing alert rule.