docs(README.md): add comment to handle React 18 createRoot API, fixes #157

Author: nluangrath-godaddy

README.md

@@ -84,6 +84,7 @@ yarn add prism-react-renderer
 ```jsx
 import React from "react";
 import { render } from "react-dom";
+// import { createRoot } from "react-dom/client";
 import Highlight, { defaultProps } from "prism-react-renderer";
 
 const exampleCode = `
@@ -111,6 +112,24 @@ render(
   </Highlight>,
   document.getElementById('root')
 );
+
+// If you are using React 18
+// const root = createRoot(document.getElementById('root'));
+// root.render(
+//  <Highlight {...defaultProps} code={exampleCode} language="jsx">
+//   {({ className, style, tokens, getLineProps, getTokenProps }) => (
+//     <pre className={className} style={style}>
+//       {tokens.map((line, i) => (
+//         <div {...getLineProps({ line, key: i })}>
+//           {line.map((token, key) => (
+//             <span {...getTokenProps({ token, key })} />
+//           ))}
+//         </div>
+//       ))}
+//     </pre>
+//   )}
+//  </Highlight>
+// )
 ```
 
 `<Highlight />` is the only component exposed by this package, as inspired by