docs: add GIF in README and logo in Doc

[charlesmindee]

This PR adds the GIF logo in the README and the PNG logo in the Sphinx documentation.
Any feedback is welcome!

[codecov]

Codecov Report

Merging #459 (31b9d95) into main (ad74838) will decrease coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main     #459      +/-   ##
==========================================
- Coverage   95.82%   95.79%   -0.03%     
==========================================
  Files          96       96              
  Lines        4023     4023              
==========================================
- Hits         3855     3854       -1     
- Misses        168      169       +1     

Flag	Coverage Δ
unittests	95.79% <ø> (-0.03%)	⬇️

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Impacted Files	Coverage Δ
...dels/detection/differentiable_binarization/base.py	91.35% <0.00%> (-0.62%)	⬇️

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[fg-mindee]

Thanks!