Update README.md to explicitly remind user to edit .env file

[cstavitsky]

No description provided.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 36.877%. Comparing base (cab39c5) to head (cc8b804).
Report is 1 commits behind head on master.

Additional details and impacted files

@@              Coverage Diff              @@
##            master       #94       +/-   ##
=============================================
- Coverage   38.762%   36.877%   -1.886%     
=============================================
  Files           10        10               
  Lines          792      1044      +252     
  Branches       255       330       +75     
=============================================
+ Hits           307       385       +78     
- Misses         476       651      +175     
+ Partials         9         8        -1     

see 10 files with indirect coverage changes

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