update event grid incoming call event sample with custom context

Author: fangchen0601

articles/event-grid/communication-services-voice-video-events.md

@@ -263,6 +263,11 @@ This section contains an example of what that data would look like for each even
       },
       "serverCallId": "tob2JIV0wzOHdab3dWcGVWZmsrL2QxYVZnQ2U1bVVLQTh1T056YmpvdXdnQjNzZTlnTEhjNFlYem5BVU9nRGY5dUFQ",
       "callerDisplayName": "John Doe",
+      "customContext": {
+        "voipHeaders": {
+          "voipHeaderName": "value"
+        }
+      },
       "incomingCallContext": "eyJhbGciOiJub25lIiwidHliSldUIn0.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.",
       "correlationId": "d732db64-4803-462d-be9c-518943ea2b7a"
     },