[i18n-KO] Translated docs: ko: pr_checks.md to Korean

[sronger]

What does this PR do?

Translated the pr_checks.md file of the documentation to Korean.
Thank you in advance for your review.

Part of #20179

Before reviewing

• Check for missing / redundant translations (번역 누락/중복 검사)
• Grammar Check (맞춤법 검사)
• Review or Add new terms to glossary (용어 확인 및 추가)
• Check Inline TOC (e.g. [[lowercased-header]])
• Check live-preview for gotchas (live-preview로 정상작동 확인)

Who can review? (Initial)

@sronger, @TaeYupNoh, @kj021, @HanNayeoniee, @eenzeenee, @sim-so

Before submitting

• This PR fixes a typo or improves the docs (you can dismiss the other checks if that's the case).
• Did you read the contributor guideline,
  Pull Request section?
• Was this discussed/approved via a Github issue or the forum? Please add a link
  to it if that's the case.
• Did you make sure to update the documentation with your changes? Here are the
  documentation guidelines, and
  here are tips on formatting docstrings.
• Did you write any new necessary tests?

Who can review? (Final)

[HuggingFaceDocBuilderDev]

The docs for this PR live here. All of your documentation changes will be reflected on that endpoint.

[sim-so]

첫 PR 고생 많으셨습니다! 🥳
마침 문서 번역을 위해 PR을 하고 있는 저희에게 참고가 되는 문서였어요.

특별한 오류를 발견하지 못해서 한국어 표현 위주로 리뷰를 드려보았는데요,
좋은 문장에 대한 생각은 모두 다를 수 있으니 모두 반영하지 않고 참고만 해주셔도 괜찮습니다! 😊

[TaeYupNoh]

LGTM!

[stevhliu]

Thanks for your translation! We've recently added a section describing how the check_copies mechanism works. Would you like to translate that section as well? :)

[sronger]

Translation completed!
May you please review this PR? :)
@sgugger, @ArthurZucker, @eunseojo, @stevhliu

[sgugger]

Thanks!