docs: Updated README and documentation

[fg-mindee]

This PR introduces the following modifications:

• adds PyTorch reference in README & documentation
• adapts the predictor description in the documentation
• updated font of documentation

Closes #341

Any feedback is welcome!

[charlesmindee]

Thanks!

[codecov]

Codecov Report

Merging #344 (60c4cf5) into main (a5bbd53) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #344      +/-   ##
==========================================
- Coverage   95.40%   95.37%   -0.03%     
==========================================
  Files          83       83              
  Lines        3393     3393              
==========================================
- Hits         3237     3236       -1     
- Misses        156      157       +1     

Flag	Coverage Δ
unittests	95.37% <ø> (-0.03%)	⬇️

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Impacted Files	Coverage Δ
...dels/detection/differentiable_binarization/base.py	91.08% <0.00%> (-0.64%)	⬇️

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