fix: warn when using SEO features without baseUrl

[BobbieGoede]

🔗 Linked issue

• Warn when using SEO features without configuring baseUrl #2941

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 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)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

Resolves #2941

Adds a warning when using SEO features without setting baseUrl, may change this to throw an error instead before creating release candidate.

📝 Checklist

• I have linked an issue or discussion.
• I have added tests (if possible).
• I have updated the documentation accordingly.

[pkg-pr-new]

Open in Stackblitz

pnpm add https://pkg.pr.new/@nuxtjs/i18n@3145

commit: 5089f83

[pkg-pr-new]

Open in Stackblitz

pnpm add https://pkg.pr.new/@nuxtjs/i18n@3145

commit: f1dafc2