Docs: move documentation to README

[ohmyfelix]

What changed

• Moved the package documentation from .docs/README.md into the root README.md.
• Removed the obsolete .docs/README.md pointer target.
• Kept the Contributte badge/contact scaffold and promoted Versions before installation.

Why

Refs contributte/contributte#75

Testing

• git diff --check

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 34.18%. Comparing base (47de678) to head (a425674).

Additional details and impacted files

@@           Coverage Diff           @@
##           master      #19   +/-   ##
=======================================
  Coverage   34.18%   34.18%           
=======================================
  Files           3        3           
  Lines         117      117           
=======================================
  Hits           40       40           
  Misses         77       77           

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