Wrap Example app in React.Strict

Author: nkbt

example/index.js

@@ -9,4 +9,4 @@ const appRoot = document.createElement('div');
 
 appRoot.id = 'app';
 document.body.appendChild(appRoot);
-ReactDOM.render(<App />, appRoot);
+ReactDOM.render(<React.StrictMode><App /></React.StrictMode>, appRoot);