Replace walkthrough-2 with notebook

[effigies]

@demidenm I got this started. You'll want to build locally (make serve) to fiddle with it.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (847574f) to head (2037180).

Additional details and impacted files

@@            Coverage Diff            @@
##              main       #98   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files            4         4           
  Lines          140       140           
=========================================
  Hits           140       140           

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