specify sys in workflow

As pointed out by @basnijholt, in the workflow illustration kwant.smatrix really should take sys as an argument.

Added 1 commit:

• 68a36435 - change sys -> syst in workflow, use smatrix(syst)

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Added 1 commit:

• 9656f66b - change sys -> syst in workflow, use smatrix(syst)

Compare with previous version

Merging after getting feedback from @cwg in chat.

Status changed to merged