docu: added ducu

react-config-tutorial/src/index.js

@@ -2,6 +2,8 @@ import React from "react";
 import ReactDOM from "react-dom";
 /*
  *component Welcome
+ *using class syntax from ES6
+ *Webpack needs Babel to process ES6 into ES5 syntaxes in order for this class to work
  */
 class Welcome extends React.Component {
   render() {