Update TOC

Author: craigshoemaker

articles/azure-functions/TOC.yml

@@ -345,7 +345,15 @@
         href: functions-bindings-cosmosdb-v2.md
         displayName: Azure Cosmos DB
     - name: Event Grid
-      href: functions-bindings-event-grid.md
+      items: 
+        - name: Overview
+          href: functions-bindings-event-grid.md
+        - name: Trigger
+          href: functions-bindings-event-grid-trigger.md
+        - name: Input
+          href: functions-bindings-event-grid-input.md
+        - name: Output
+          href: functions-bindings-event-grid-output.md
     - name: Event Hubs
       href: functions-bindings-event-hubs.md
     - name: IoT Hub