Remove preview in ToC

Author: austonli

articles/azure-monitor/toc.yml

@@ -522,7 +522,7 @@ items:
           href: containers/container-insights-agent-config.md
         - name: Enable ContainerLogv2
           href: containers/container-insights-logging-v2.md
-        - name: Enable cost optimization settings (preview)
+        - name: Enable cost optimization settings
           href: containers/container-insights-cost-config.md
         - name: Authentication
           href: containers/container-insights-authentication.md