Updated env example file

.env.example

@@ -1,5 +1,6 @@
-CLIENT_ID=<SERVICE PRINCIPAL CLIENT ID>
-CLIENT_SECRET=<SERVICE PRINCIPAL SECRET>
+ENGINE_APP_ID=<ENGINE SERVICE PRINCIPAL CLIENT ID>
+ENGINE_APP_SECRET=<ENGINE SERVICE PRINCIPAL SECRET>
+UI_APP_ID=<UI SERVICE PRINCIPAL CLIENT ID>
 TENANT_ID=<AZURE AD TENANT ID>
 COSMOS_URL=https://<COSMOS NAME>.documents.azure.com
 COSMOS_KEY=<COSMOS ACCESS KEY>