docs: add Japanese README

[eltociear]

Description

I created Japanese translated README.

Type of Change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Refactoring (no functional changes, no api changes)
• Documentation update
• CI/CD or Build changes

Current Behavior

Updated/Expected Behavior

Implementation Details

Screenshots / Recordings

Checklist

• My code follows the code style of this project
• I have performed a self-review of my own code
• I have added XML documentation to any related classes

Breaking Changes

Obsoletions / Deprecations

Fixed Issues

[github-actions]

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