Mention generate in README.md

[ogauthe]

solves #44

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 72.28%. Comparing base (9cfd842) to head (a9d42ed).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##            main      #45       +/-   ##
==========================================
+ Coverage   6.02%   72.28%   +66.26%     
==========================================
  Files          1        1               
  Lines         83       83               
==========================================
+ Hits           5       60       +55     
+ Misses        78       23       -55     

Flag	Coverage Δ
docs	72.28% <ø> (+72.28%)	⬆️

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