Fix polygon plots in docs

[stefmolin]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 98.49%. Comparing base (73b6bc0) to head (a4db7a4).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #270   +/-   ##
=======================================
  Coverage   98.49%   98.49%           
=======================================
  Files          60       60           
  Lines        1925     1925           
  Branches      113      113           
=======================================
  Hits         1896     1896           
  Misses         26       26           
  Partials        3        3           

Files with missing lines	Coverage Δ
src/data_morph/shapes/factory.py	100.00% <ø> (ø)
src/data_morph/shapes/lines/diamond.py	100.00% <ø> (ø)
src/data_morph/shapes/lines/rectangle.py	100.00% <ø> (ø)
src/data_morph/shapes/lines/star.py	100.00% <ø> (ø)
tests/shapes/test_polygons.py	100.00% <100.00%> (ø)