[Docs] Add QR code in CN README

[zhouzaida]

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[codecov]

Codecov Report

Merging #954 (83d2f0a) into master (1bc912e) will not change coverage.
The diff coverage is n/a.

❗ Current head 83d2f0a differs from pull request most recent head 3d613b6. Consider uploading reports for the commit 3d613b6 to get more accurate results

@@           Coverage Diff           @@
##           master     #954   +/-   ##
=======================================
  Coverage   65.64%   65.64%           
=======================================
  Files         149      149           
  Lines        9455     9455           
  Branches     1722     1722           
=======================================
  Hits         6207     6207           
  Misses       2928     2928           
  Partials      320      320           

Flag	Coverage Δ
unittests	65.64% <ø> (ø)

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