chore: improve doctests & axum test a bit

[matheus23]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 0% with 4 lines in your changes are missing coverage. Please review.

Project coverage is 50.72%. Comparing base (206f6d8) to head (35defb0).

Additional details and impacted files

@@            Coverage Diff             @@
##             main      #43      +/-   ##
==========================================
+ Coverage   50.39%   50.72%   +0.32%     
==========================================
  Files          15       15              
  Lines         758      759       +1     
  Branches      358      358              
==========================================
+ Hits          382      385       +3     
  Misses         65       65              
+ Partials      311      309       -2     

Files	Coverage Δ
car-mirror/src/lib.rs	100.00% <ø> (ø)
car-mirror-reqwest/integration/axum.rs	28.98% <0.00%> (-0.43%)	⬇️

... and 2 files with indirect coverage changes