Update toc.yml

Author: ddematheu2

articles/communication-services/toc.yml

@@ -332,6 +332,10 @@ items:
             href: concepts/interop/teams-user/government-cloud.md
   - name: Network Traversal (TURN)
     href: concepts/network-traversal.md    
+  - name: Developer Tools
+    items:
+      - name: Network Diagnostic Tool
+        herf: concepts/developer-tools/network-diagnostic.md
   - name: Data residency and user privacy
     href: concepts/privacy.md
   - name: Azure Government