[demo/docs] Update notebook docs & minor demo update / fix

[felixT2K]

This PR:

• Add new notebooks to docs
• Fix font issue in demo & expose export_as_straight_boxes to users

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.47%. Comparing base (7f21e76) to head (3ebf33a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1755      +/-   ##
==========================================
- Coverage   96.49%   96.47%   -0.03%     
==========================================
  Files         164      164              
  Lines        7881     7881              
==========================================
- Hits         7605     7603       -2     
- Misses        276      278       +2     

Flag	Coverage Δ
unittests	96.47% <100.00%> (-0.03%)	⬇️

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