docs: update wording for server-side usage

[hansemannn]

🔗 Linked issue

https://github.com/nuxt-modules/i18n/issues/2715

❓ Type of change

• [x] 📖 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

Resolves a few docs issues regarding server-side i18n.

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

[nuxt-studio[bot]]

✅ Live Preview ready!

Name	Edit	Preview	Latest Commit
i18n	Edit on Studio ↗︎	View Live Preview	108d62c894f9283c12d1c074a218347da19fc76e

[BobbieGoede]

Thanks for contributing!