docs: migrate ReactDOM.render to createRoot for React 18+

[Samii2383]

This PR updates the example in single-file-example.html to use React 18+ createRoot API instead of the deprecated ReactDOM.render.

• Replaced:
  ReactDOM.render(

  Hello, world!

  , document.getElementById('root'));
• With:
  const root = ReactDOM.createRoot(document.getElementById('root'));
  root.render(

  Hello, world!

  );

This ensures compatibility with React 18 and follows current best practices.

[meta-cla]

Hi @Samii2383!

Thank you for your pull request and welcome to our community.

Action Required

In order to merge any pull request (code, docs, etc.), we require contributors to sign our Contributor License Agreement, and we don't seem to have one on file for you.

Process

In order for us to review and merge your suggested changes, please sign at https://code.facebook.com/cla. If you are contributing on behalf of someone else (eg your employer), the individual CLA may not be sufficient and your employer may need to sign the corporate CLA.

Once the CLA is signed, our tooling will perform checks and validations. Afterwards, the pull request will be tagged with CLA signed. The tagging process may take up to 1 hour after signing. Please give it that time before contacting us about it.

If you have received this in error or have any questions, please contact us at cla@meta.com. Thanks!

[github-actions]

Size changes

Details

📦 Next.js Bundle Analysis for react-dev

This analysis was generated by the Next.js Bundle Analysis action. 🤖

This PR introduced no changes to the JavaScript bundle! 🙌

[meta-cla]

Thank you for signing our Contributor License Agreement. We can now accept your code for this (and any) Meta Open Source project. Thanks!

[Samii2383]

Hi maintainers, the CLA is signed and all checks have passed. Please let me know if anything else is needed to merge this PR.

[rickhanlonii]

Thanks but this doesn't work