removing duplicate toc node

Author: batamig

articles/defender-for-iot/organizations/TOC.yml

@@ -215,8 +215,6 @@
         href: how-to-troubleshoot-the-sensor-and-on-premises-management-console.md
 - name: Reference
   items:
-  - name: Alert reference
-    href: alert-engine-messages.md
   - name: OT monitoring appliances
     items:
     - name: Overview