docs(firebase): improve docs

[luc122c]

🔗 Linked issue

Fixes #1555

❓ 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 tried implementing the new Gen2 preset, and noticed there were a couple of inconsitencies between the code, and the docs. This PR fixes them.

📝 Checklist

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

[nuxt-studio]

✅ Live Preview ready!

Name	Edit	Preview	Latest Commit
nitro	Edit on Studio ↗︎	View Live Preview	37151de

[codecov]

Codecov Report

Merging #1556 (37151de) into main (7fa8408) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1556   +/-   ##
=======================================
  Coverage   76.49%   76.49%           
=======================================
  Files          73       73           
  Lines        7580     7580           
  Branches      751      751           
=======================================
  Hits         5798     5798           
  Misses       1781     1781           
  Partials        1        1           

[pi0]

Thanks!