doc: Update README

[jamacku]

• fix badges
• drop section related to testing

[codecov-commenter]

Codecov Report

Merging #69 (e9c3455) into main (31126b8) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main      #69   +/-   ##
=======================================
  Coverage   73.88%   73.88%           
=======================================
  Files           5        5           
  Lines         134      134           
=======================================
  Hits           99       99           
  Misses         35       35           

Flag	Coverage Δ
integration	0.00% <ø> (ø)
unit	73.88% <ø> (ø)

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