fix rules issues for update_external_docs workflow

[bjohansebas]

Changes are made to run the workflow correctly and prevent this workflow from running in a forked repository.

Changes:

• Now the workflow will only run in the main repository (expressjs/expressjs.com).
• The tool is updated to use an external action allowed by the organization.
• Automatically add the review for the @expressjs/docs-wg team.
• Update the checkout action to its latest version

[netlify]

✅ Deploy Preview for expressjscom-preview ready!

Name	Link
🔨 Latest commit	7e181e3
🔍 Latest deploy log	https://app.netlify.com/sites/expressjscom-preview/deploys/66e0fbd775d744000820df09
😎 Deploy Preview	https://deploy-preview-1606--expressjscom-preview.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.