[fix] Demo using containsMany (#1586)

Author: ibelar

demos/special/multiline-containsmany.php

@@ -21,7 +21,7 @@ protected function init(): void
         parent::init();
 
         $this->addField('name');
-        $this->containsMany('Accounts', [Account::class]);
+        $this->containsMany('Accounts', ['model' => [Account::class]]);
     }
 }