Update reference TOC

Author: Microsoft Graph DevX Tooling

api-reference/beta/toc/teamwork-and-communications/toc.yml

@@ -819,6 +819,10 @@ items:
       href: ../../api/sharedwithchannelteaminfo-list-allowedmembers.md
     - name: Check user access
       href: ../../api/channel-doesuserhaveaccess.md
+    - name: Planner
+      items:
+      - name: List plans
+        href: ../../api/teamschannelplanner-list-plans.md
   - name: Chat
     items:
     - name: Chat