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 89.65%. Comparing base (41d0d4b) to head (80587da).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2800      +/-   ##
==========================================
+ Coverage   89.60%   89.65%   +0.04%     
==========================================
  Files         174      174              
  Lines        8450     8450              
  Branches     1660     1660              
==========================================
+ Hits         7572     7576       +4     
+ Misses        878      874       -4     

see 1 file with indirect coverage changes

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