Incorporate graphics from Lea's 4 Dec talk

[karllark]

Great figures on the flow of a BEAST run in @lea-hagen's 4 Dec 2020 talk during HackDay. Would be great to get at least some of them integrated into the docs.

[christinawlindberg]

Are you referring to the hand-drawn ones?

[karllark]

There were multiple figures that I found useful in her presentation. Some of them were your work - and those should be included as well!

[lea-hagen]

For reference, here's the talk: https://speakerdeck.com/lhagen/the-beast-downloading-my-brain/