Emphasize the necessity of creating a D1 database and how to configure wrangler so nuxi preview works.

🔗 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

Changes

• Places more emphasis on a D1 database being required
• Provides a minimal example wrangler config for running preview locally
• Explains what this example config does
• Links to Nuxt Content's docs section for D1 configuration
• Links more directly to Cloudflare's documentation about creating and binding a D1 database

Why

My initial reading of the statement that the module will "prepare the necessary configuration" caused me to misunderstand the importance of D1 being required. I think the new emphasis should help prevent that misreading.

I also had trouble running nuxi preview locally to check a mismatch between local and prod behavior. I no longer recall if nuxi preview actually helped me solve my problems, but I suspect other people probably don't want to be stuck configuring preview when they think it will help debugging something else.

For context, the issues I was debugging (and have since resolved) were:

• Some content not loading correctly. This was likely because another source told me to use generate instead of build, and I then also didn't have D1 set up.
• An infinite 404 loop. This was likely caused by the fact that I didn't have an error.vue file and the fact that my default slug was throwing a 404 when content was missing. But local dev was ok because it provides an error page.
• A file I created postbuild wasn't being added to _routes, because _routes is created during build and I didn't understand that part of Cloudflare enough to expect the issue.

📝 Checklist

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