docs: add "supported" statement to the library

[susnux]

☑️ Resolves

Add statement about the support state on this library - not yet taking Vue2 deprecation into account just the current state.

🏁 Checklist

• ⛑️ Tests are included or are not applicable
• 📘 Component documentation has been extended, updated or is not applicable
• 2️⃣ Backport to stable8 for maintained Vue 2 version or not applicable

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 58.49%. Comparing base (e5aa44e) to head (a4805db).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #9006   +/-   ##
=======================================
  Coverage   58.49%   58.49%           
=======================================
  Files         124      124           
  Lines        4465     4465           
  Branches     1330     1330           
=======================================
  Hits         2612     2612           
  Misses       1574     1574           
  Partials      279      279           

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