doc(config-tutorial): add React v18 note

config-tutorial/src/index.js

@@ -1,5 +1,4 @@
 import React from 'react';
-import ReactDOM from 'react-dom';
 import './style/main.less';
 
 /*
@@ -12,4 +11,13 @@ class Welcome extends React.Component {
         return <h1>react-config-tutorial</h1>;
     }
 }
-ReactDOM.render(<Welcome />, document.getElementById('root'));
+/*ReactDOM.render is no longer supported in React 18. Use createRoot instead.*/
+import { createRoot } from 'react-dom/client';
+//create root container
+const root = createRoot(document.getElementById('root'));
+//render root app
+root.render(
+    <React.StrictMode>
+        <Welcome />
+    </React.StrictMode>
+);