Add Visualizations section to README.md

[RandomFractals]

• Move pandas/matplotlib ipynb info and pic to new vizes section
• Add new Altair ipynb section with a gif from #32
• Move with Malloy charts pic and info to new vizes secition
• Add PyScript page info from #30 to new vizes section

[RandomFractals]

See https://github.com/RandomFractals/chicago-crimes#visualizations