docs: fix ProseCode preview syntax highlighting

[BobbieGoede]

🔗 Linked issue

• Inline code is not highlighted #2805

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Resolves #2805

before

after

BTW, the divider preview is broken, since parent div uses display flex (and I think the divider color matches the background in dark mode)

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[vercel]

@BobbieGoede is attempting to deploy a commit to the NuxtLabs Team on Vercel.

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[pkg-pr-new]

npm i https://pkg.pr.new/@nuxt/content@3491

commit: 746fe82