docs: display the component-owner role more prominently in README.md

[pichlermarc]

How maintenance in the the contrib repo works is kind of hidden away, and many people assume it works similarly to the core repo where there's shared ownership across the whole repo, which is not completely the case here.

This puts info about component ownership more prominently into the README.md, and clarifies that packages here are community maintained for the most part.

I plan to follow-up with a new document with role descriptions (split from CONTRIBUTING.md) to clarify further, as well as a new document for component maintenance status lifecycle (including a process for removal of unmaintained components).

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 89.67%. Comparing base (f6bc4cc) to head (8eaca9a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2800   +/-   ##
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  Coverage   89.67%   89.67%           
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  Files         184      184           
  Lines        8946     8946           
  Branches     1834     1834           
=======================================
  Hits         8022     8022           
  Misses        924      924           

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