TropicalGeometry + PolyhedralGeometry: fixing references in documentation

[YueRen]

Beginning fixing some documentation as discussed in #3915

Does anybody know how to correctly add a reference to the function rays for polyhedral complexes? Currently, [`rays(::PolyhedralComplex)`](@ref) links to rays for K3Chamber.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 84.57%. Comparing base (2008cc6) to head (4c36ba7).
Report is 8 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3923      +/-   ##
==========================================
+ Coverage   84.55%   84.57%   +0.01%     
==========================================
  Files         596      597       +1     
  Lines       81994    82179     +185     
==========================================
+ Hits        69330    69502     +172     
- Misses      12664    12677      +13     

Files	Coverage Δ
src/PolyhedralGeometry/Cone/properties.jl	90.24% <ø> (ø)
...PolyhedralGeometry/PolyhedralComplex/properties.jl	86.27% <ø> (ø)
src/PolyhedralGeometry/PolyhedralFan/properties.jl	98.33% <ø> (ø)
src/PolyhedralGeometry/Polyhedron/properties.jl	86.50% <ø> (ø)
...edralGeometry/Polyhedron/standard_constructions.jl	97.33% <ø> (ø)
src/TropicalGeometry/hypersurface.jl	88.13% <ø> (ø)
src/TropicalGeometry/variety_supertype.jl	44.64% <ø> (ø)

... and 9 files with indirect coverage changes

[YueRen]

Modulo bugs that are currently affecting the entire documentation, see #4009, I think the pull request is ready to be reviewed.

The goal of the pull request is to make the documentation more explicit whilst keeping it slim by adding references to same-named functions in polyhedral geometry.

[YueRen]

@lkastner Could you review the changes for me, please? I've had to add some bits to the documentation in polyhedral geometry, let me know if you are okay with that.