Add API Center MCP registry URL

The API Center MCP registry URL is not documented anywhere, adding it to the documentation to help with the setup.

Author: luizbon

content/copilot/how-tos/administer-copilot/configure-mcp-server-access.md

@@ -196,5 +196,9 @@ For enterprises that want a dynamic and fully managed option, Azure API Center (
 
 > [!NOTE]
 > Azure API Center includes a free tier for basic API cataloging and discovery. Larger organizations may choose to use paid Azure API Management plans for higher scale and advanced governance.
+>
+> The Azure API Center URL serving the MCP Registry is the **Runtime URL** suffixed with `/workspaces/default/v0/servers`.
+> 
+> **Example**: https://{api-center-name}.data.{location}.azure-apicenter.ms/workspaces/default/v0/servers
 
 For more information, see [Azure API Center Documentation](https://learn.microsoft.com/en-us/azure/api-center/) and [Azure API Center Quickstart](https://learn.microsoft.com/en-us/azure/api-center/set-up-api-center).