Intersection theory: correct bug, add more examples

[wdecker]

No description provided.

[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 2 lines in your changes missing coverage. Please review.

Project coverage is 84.48%. Comparing base (aea00d0) to head (7b085d7).
Report is 1 commits behind head on master.

Files with missing lines	Patch %	Lines
experimental/IntersectionTheory/src/Main.jl	50.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #4269      +/-   ##
==========================================
- Coverage   84.48%   84.48%   -0.01%     
==========================================
  Files         641      641              
  Lines       85427    85429       +2     
==========================================
+ Hits        72170    72171       +1     
- Misses      13257    13258       +1     

Files with missing lines	Coverage Δ
experimental/IntersectionTheory/src/Main.jl	93.27% <50.00%> (+0.19%)	⬆️

... and 1 file with indirect coverage changes