update toc

Author: fangchen0601

articles/communication-services/toc.yml

@@ -478,6 +478,8 @@ items:
         href: how-tos/call-automation/secure-webhook-endpoint.md
       - name: Handling Call Automation Events with EventProcessor
         href: how-tos/call-automation/handle-events-with-event-processor.md
+      - name: How to pass call contextual data in Call Automation
+        href: how-tos/call-automation/custom-context.md
     - name: Call recording
       items:
       - name: Record a call