docs: fix link to rehype

[Mogyuchi]

Pre-flight checklist

• I have read the Contributing Guidelines on pull requests.
• If this is a code change: I have written unit tests and/or added dogfooding pages to fully verify the new behavior.
• If this is a new API or substantial change: the PR has an accompanying issue (closes #0000) and the maintainers have approved on my working plan.

Motivation

I found that the link that should refer to the Rehype documentation was linking toward Remark. Therefore, I have modified the link to link toward Rehype.

Test Plan

1. Click the link

Test links

Deploy preview: https://deploy-preview-9018--docusaurus-2.netlify.app/docs/markdown-features/plugins#creating-new-rehyperemark-plugins

Related issues/PRs

[netlify]

✅ [V2]

Built without sensitive environment variables

Name	Link
🔨 Latest commit	b6d8a90
🔍 Latest deploy log	https://app.netlify.com/sites/docusaurus-2/deploys/6474127a4ff1dc0009d8c985
😎 Deploy Preview	https://deploy-preview-9018--docusaurus-2.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 settings.

[github-actions]

⚡️ Lighthouse report for the deploy preview of this PR

URL	Performance	Accessibility	Best Practices	SEO	PWA	Report
/	🟠 89	🟢 97	🟢 100	🟢 100	🟠 89	Report
/docs/installation	🟠 79	🟢 100	🟢 100	🟢 100	🟠 89	Report

[slorber]

Thanks 👍