Update part1c.md

avoid error in example:
"main.jsx:12 Warning: You are calling ReactDOMClient.createRoot() on a container that has already been passed to createRoot() before. Instead, call root.render() on the existing root instead if you want to update it."

Author: sjtower

src/content/1/en/part1c.md

@@ -216,8 +216,10 @@ the component won't re-render. We can get the component to re-render by calling
 ```js
 let counter = 1
 
+const root = ReactDOM.createRoot(document.getElementById('root'))
+
 const refresh = () => {
-  ReactDOM.createRoot(document.getElementById('root')).render(
+  root.render(
     <App counter={counter} />
   )
 }