docs: remove RC reference and add link to vue migration build

[gangsthub]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme or JSdoc annotations)
• 🐞 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)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

I don't know if this still stands true, but the "RC" reference seemed outdated.

I've also added a link to the @vue/compat library (AKA Migration Build), for clarity.

Please, let me know if the PR description is missing something. 🙏🏽

📝 Checklist

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

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[danielroe]

Nice - thanks!