address issues raised by review

Author: Boris Bazilevskiy

articles/communication-services/toc.yml

@@ -715,6 +715,8 @@ items:
           href: concepts/telephony/monitoring-troubleshooting-telephony/troubleshoot-tls-certificate-sip-options.md
         - name: Troubleshoot outbound calls
           href: concepts/telephony/monitoring-troubleshooting-telephony/troubleshoot-outbound-calls.md
+        - name: SIP protocol details for direct routing
+          href: concepts/telephony/direct-routing-sip-specification.md
     - name: Call Automation
       items:
       - name: Overview