docs: visualize Topology with node IDs

[redeboer]

• The visualize page now also illustrates how to visualize topologies.
• It's now possible to run convert_to_dot on a tuple as well. This is required if one wants to do:

  from expertsystem.io import convert_to_dot
  from expertsystem.reaction.topology import create_isobar_topologies
  convert_to_dot(create_isobar_topologies(4))

  because create_isobar_topologies returns a tuple.
• Node IDs are also rendered in DOT if there is more than one node

[codecov]

Codecov Report

Merging #501 (4a57409) into master (6e00fbb) will decrease coverage by 0.04%.
The diff coverage is 87.50%.

@@            Coverage Diff             @@
##           master     #501      +/-   ##
==========================================
- Coverage   89.20%   89.16%   -0.05%     
==========================================
  Files          22       22              
  Lines        3336     3341       +5     
  Branches      844      847       +3     
==========================================
+ Hits         2976     2979       +3     
- Misses        195      196       +1     
- Partials      165      166       +1     

Flag	Coverage Δ
unittests	89.16% <87.50%> (-0.05%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/expertsystem/io/__init__.py	75.00% <50.00%> (-1.93%)	⬇️
src/expertsystem/io/_dot.py	79.61% <100.00%> (+2.84%)	⬆️
src/expertsystem/amplitude/helicity_decay.py	89.57% <0.00%> (-0.78%)	⬇️