update per case feedback

From: Alice Cunningham <[email protected]> 
To: John Kemnetz <[email protected]>; Rob Boucher <[email protected]>
Subject: [Azure Monitor Docs] Mismatching info in Supported services, schemas, and categories for Azure Diagnostic Logs page 

Hi John and Rob,

Hope your week is going well. 

I’m the Support Escalation Engineer from Azure Rapid Response team. I have a case with our premier customer, they are currently utilizing the azure CLI and monitor feature to stream the diagnostics logs to event hub. However, while working on webex with them, we noticed that some information aren’t matching what we see in the portal (both external and internal user portal), please see two items below. Your help will be much appreciated. Thank you in advance.

Author: rboucher

articles/azure-monitor/platform/diagnostic-logs-schema.md

@@ -82,6 +82,9 @@ The schema for resource diagnostic logs varies depending on the resource and log
 | Virtual Network Gateways | Schema not available. |
 
 ## Supported log categories per resource type
+
+Some categories may only be supported for specific types of resources. This is list of all that are available in some form.  For example, Microsoft.Sql/servers/databases categories aren't available for all types of databases. For more information, see [information on SQL Database diagnostic logging](../../sql-database/sql-database-metrics-diag-logging.md). 
+
 |Resource Type|Category|Category Display Name|
 |---|---|---|
 |Microsoft.AAD/domainServices|SystemSecurity|SystemSecurity|