Fix a typo in shortcut Japanese document

[seratch]

Summary

Sorry, my updates on the Japanese document included a typo. This pull request fixes it.

Requirements (place an x in each [ ])

• I've read and understood the Contributing Guidelines and have done my best effort to follow them.
• I've read and agree to the Code of Conduct.

[codecov]

Codecov Report

Merging #432 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #432   +/-   ##
=======================================
  Coverage   79.77%   79.77%           
=======================================
  Files           7        7           
  Lines         544      544           
  Branches      158      158           
=======================================
  Hits          434      434           
  Misses         80       80           
  Partials       30       30

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