Update visualisation docs

[EwoutH]

Update the visualisation docs to the new visualisation method.

• API documentation
• Docstring

[EwoutH]

Trying to optimize this page: https://mesa--2162.org.readthedocs.build/en/2162/apis/visualization.html

[EwoutH]

I think it now looks really nice, and I think it's an useful additional source of information to get started with the new visualisation.

Ready for review! Please squash on merge.

[github-actions]

Performance benchmarks:

Model	Size	Init time [95% CI]	Run time [95% CI]
Schelling	small	🔵 +0.2% [-0.1%, +0.4%]	🔵 -0.9% [-1.1%, -0.7%]
Schelling	large	🔵 +0.3% [+0.0%, +0.6%]	🔵 -0.7% [-1.5%, +0.2%]
WolfSheep	small	🔵 +0.7% [-0.1%, +1.5%]	🔵 -1.3% [-1.6%, -1.1%]
WolfSheep	large	🔵 +0.5% [-0.0%, +1.0%]	🔵 +1.4% [-0.2%, +3.2%]
BoidFlockers	small	🔵 +0.7% [+0.2%, +1.4%]	🔵 -0.9% [-1.6%, -0.2%]
BoidFlockers	large	🔵 -0.1% [-0.9%, +0.7%]	🔵 -1.1% [-1.9%, -0.3%]