docs: add Japanese README

[eltociear]

I created Japanese translated README.

[github-actions]

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Validation Report

Validation	Active	Result
All commits in this pull request has valid messages	❌	✅
Pull request does not introduce too many changes	❌	✅
Pull request has a valid title	✅	✅
Pull request has mentioned issues	❌	✅
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Pull request should have a non-empty body	✅	✅

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Pull request satisfies all enabled pull request rules.

_{Last Modified at 17 Jul 24 15:44 UTC}

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[anovazzi1]

大丈夫