Updating Table of contents

Author: pgrandhi

articles/communication-services/toc.yml

@@ -20,6 +20,8 @@ items:
       href: quickstarts/identity/access-tokens.md
     - name: Get a phone number
       href: quickstarts/telephony/get-phone-number.md
+    - name: Subscribe to events
+      href: quickstarts/events/subscribe-to-events.md
     - name: SDKs and APIs
       href: concepts/sdk-options.md
     - name: Designing your architecture