Update Japanese translation guide

[shu-mutou]

No description provided.

[ziyi-xie]

/lgtm

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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[codecov]

Codecov Report

Merging #7628 (333febd) into master (bc518f7) will increase coverage by 1.30%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #7628      +/-   ##
==========================================
+ Coverage   42.16%   43.47%   +1.30%     
==========================================
  Files         217       54     -163     
  Lines       12092     1265   -10827     
  Branches      179      179              
==========================================
- Hits         5099      550    -4549     
+ Misses       6708      677    -6031     
+ Partials      285       38     -247