Fix ES6 comma-dangle eslint rule (functions should be ignored pre-ES2017) [MAILPOET-1028]

assets/js/src/help/help.jsx

@@ -11,7 +11,7 @@ const history = useRouterHistory(createHashHistory)({ queryKey: false });
 const App = React.createClass({
   render() {
     return this.props.children;
-  }
+  },
 });
 
 const container = document.getElementById('help_container');