chore: cleanup deprecated z re-export and editor usage

[maximepvrt]

This PR updates the migration guide for the deprecations (z re-export and direct .editor() usage). It would be good to mention this in the release notes for the version so users are aware of the changes.

🔗 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 like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

📝 Checklist

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

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[pkg-pr-new]

npm i https://pkg.pr.new/@nuxt/content@3561

commit: 72ffdd2

[farnabaz]

Thanks ❤️

[maximepvrt]

@farnabaz can you update the release notes for v3.7.0 to include the .editor() migration from deprecation?