Update readme_kr.md

[YJHeo01]

Previous version: The ranks consisted of S+ (top 1%), S (top 25%), A++ (top 45%), A+ (top 60%), and B+ (entire group).

Revised version: The ranks are composed of S (top 1%), A+ (top 12.5%), A (top 25%), A- (top 37.5%), B+ (top 50%), B (top 62.5%), B- (top 75%), C+ (top 87.5%), and C (top 100%)."

[vercel[bot]]

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[rickstaa]

Thank you for your contribution! We’ve decided to remove the translated README in order to simplify repository maintenance. In the future, we plan to introduce an AI-based solution for translations. We appreciate your understanding.