A statement indicating that the Agents feature in hub-based projects is currently in preview.

To avoid any confusion for all users, the document should clearly state at the beginning that the monitoring feature for Agents in hub-based projects (that has only preview Agents featre) is also a preview feature.
 
Background:
The metrics described in this document (titled "Monitor Azure AI Foundry Agent Service") are only applicable to hub-based projects.  
Additionally, the Agents feature in hub-based projects is still in preview, as explained in the document below.  

- What is Azure AI Foundry? - Azure AI Foundry | Microsoft Learn
https://learn.microsoft.com/en-us/azure/ai-foundry/what-is-azure-ai-foundry#which-type-of-project-do-i-need

"Agents / Foundry Project（GA）/ hub based project (Preview only)"

Author: noueh

articles/ai-foundry/agents/how-to/metrics.md

@@ -15,6 +15,8 @@ ms.service: azure-ai-agent-service
 
 Monitoring is available for agents in a [standard agent setup](../concepts/standard-agent-setup.md).
 
+[!INCLUDE [Feature preview](https://github.com/MicrosoftDocs/azure-ai-docs/blob/main/articles/ai-foundry/openai/includes/preview-feature.md)]
+
 > [!IMPORTANT]
 > Monitoring support is currently limited to Azure AI Foundry hubs. Azure AI Foundry projects are not supported.
 
@@ -94,4 +96,4 @@ You can set alerts for any metric listed in the [monitoring data reference](../r
 ## Related content
 
 - See [Monitoring data reference](../reference/monitor-service.md) for a reference of the metrics and other important values created for Azure AI Foundry Agent Service.
-- See [Monitoring Azure resources with Azure Monitor](/azure/azure-monitor/essentials/monitor-azure-resource) for general details on monitoring Azure resources.
+- See [Monitoring Azure resources with Azure Monitor](/azure/azure-monitor/essentials/monitor-azure-resource) for general details on monitoring Azure resources.