fix(nuxt): add catchall paths to prerender list

[danielroe]

🔗 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

Where users had only a catchall but no other pages, we weren't generating anything. In this case we can almost certainly render the base URL that would otherwise be caught by the catchall. (I've also included optional params, e.g. ~/pages/[[something]].vue.)

📝 Checklist

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

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