docs(api): add <NuxtWelcome /> component docs

[umutiq]

🔗 Linked issue

resolves nuxt/nuxt#14613

❓ 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

Solves nuxt/nuxt#14613

📝 Checklist

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

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[pi0]

Do you mind to add a ::ReadMore link to https://github.com/nuxt/ui?

[umutiq]

@pi0 Since we didn't mention it's imported from @nuxt/ui, i think it's inapporpriate.

[danielroe]

Maybe we should mention it then. I think it would be a good idea for people to know where (for example) to make PRs if they have improvements.

[umutiq]

@danielroe I added alert and Readmore links to document. Can you check it?

[pi0]

Thanks <3

[BD103]

Thank you!