docs(migration): add redirects for v1

[clemcode]

❓ 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

This PR adds 302 redirects for v1 URLs

Ex:

/installation /v1/installation 302!
/:locale/installation /:locale/v1/installation 302!

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[Tahul]

I think we should update paths.

I updated the structure so we have exact same routes for each pages.

The redirections written here won't follow correct paths.

https://deploy-preview-1123--nuxt-content.netlify.app/v1/en/getting-started/installation

You can browse actual V1 routes there; the only exception is that routes will become:

/v1/getting-started/installation => default locale (en)
/:locale/v1/getting-started/installation => localized path (fr, ja, ..)