docs: migration guide

[GalacticHypernova]

🔗 Linked issue

❓ 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)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Work in progress migration guide from Nuxt UI v2 to Nuxt UI v3. None of the phrasing is final and is likely to change as I gather everything necessary and as it gets refined

📝 Checklist

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

[pkg-pr-new]

npm i https://pkg.pr.new/@nuxt/ui@2871

commit: 7ccca37

[GalacticHypernova]

@benjamincanac should I also include UI Pro changes in here or keep it a separate migration guide? If the latter, I may need a little bit of help with the module selection 😅

[benjamincanac]

We can just do Nuxt UI for now and later on we'll either make another page for UI Pro or integrate it in the same page with the :module-only component.

[GalacticHypernova]

Sounds good to me! I'll start testing components to see what was changed, hopefully I'll find it all