[readme] Update broken link for configuration files

[prateek3255]

Fix broken link to ESLint docs in README

[ljharb]

unfortunate it broke in the first place - cool URLs don't change - but thanks for the update

[codecov-commenter]

Codecov Report

Merging #3071 (bd270fc) into master (f4854ea) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #3071   +/-   ##
=======================================
  Coverage   97.43%   97.43%           
=======================================
  Files         111      111           
  Lines        7529     7529           
  Branches     2769     2769           
=======================================
  Hits         7336     7336           
  Misses        193      193           

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