docs: improve README

[JounQin]

No description provided.

[codecov]

Codecov Report

Merging #23 into master will not change coverage.
The diff coverage is n/a.

@@          Coverage Diff           @@
##           master     #23   +/-   ##
======================================
  Coverage    81.1%   81.1%           
======================================
  Files          21      21           
  Lines         254     254           
  Branches       26      26           
======================================
  Hits          206     206           
  Misses         47      47           
  Partials        1       1

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