Add mermaid to list of supported languages

[dylans]

Excalidraw has a mermaid to excalidraw plugin, so we should add mermaid to the list of languages to make it easier for someone to add a convert from mermaid to excalidraw option.

Checklist

• yarn typecheck
• yarn lint:fix
• yarn test
• yarn brl
• yarn changeset
• ui changelog

[vercel]

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Name	Status	Preview	Comments	Updated (UTC)
plate	✅ Ready (Inspect)	Visit Preview	💬 Add feedback	Aug 12, 2024 0:14am

[changeset-bot]

⚠️ No Changeset found

Latest commit: d91dbe3

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[dylans]

Note, I'm not sure if I have the package name correct for the changelog.

This is part of some work I'm doing to update excalidraw so that it will actually work for people more easily out of the box.

[zbeyens]

You can remove that changeset, you'll just need to update https://github.com/udecode/plate/blob/main/apps/www/content/docs/components/changelog.mdx since it's not part of the packages