Merge pull request #11031 from hamed-zeidabadi/fix/update-react-18-api-in-readme

docs: update README to use React 18 createRoot API

Author: djhi

README.md

@@ -47,13 +47,13 @@ yarn add react-admin
 ```jsx
 // in app.js
 import * as React from "react";
-import ReactDOM from 'react-dom';
+import { createRoot } from 'react-dom/client';
 import { Admin, Resource } from 'react-admin';
 import restProvider from 'ra-data-simple-rest';
 
 import { PostList, PostEdit, PostCreate, PostIcon } from './posts';
 
-ReactDOM.createRoot(document.getElementById('root')!).render(
+createRoot(document.getElementById('root')!).render(
     <Admin dataProvider={restProvider('http://localhost:3000')}>
         <Resource name="posts" list={PostList} edit={PostEdit} create={PostCreate} icon={PostIcon} />
     </Admin>