add readme for local server instruction

[minhsueh]

^^

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 85.52%. Comparing base (398deab) to head (00cfa31).
⚠️ Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #1451   +/-   ##
========================================
  Coverage    85.52%   85.52%           
========================================
  Files          229      229           
  Lines        18784    18784           
========================================
  Hits         16065    16065           
  Misses        2719     2719           

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[esoteric-ephemera]

Thanks @minhsueh!