chore: enhance the pr/issue templates

[sungik-choi]

Summary

GitHub PR과 이슈 템플릿을 개선합니다.

Details

• 오픈소스임을 감안하여 모두 영문으로 변경했습니다.
• PR 템플릿에 셀프 체크리스트를 추가했습니다. 명시적으로 작성되지 않던 규칙들을 추가했습니다 (TODO: Contribute 문서에도 추가 필요)

Browser Compatibility

References

• Chakra UI, Shopify Polaris 참고
• prosemirror-toolkit의 PR 템플릿 셀프 체크리스트 참고

[changeset-bot]

⚠️ No Changeset found

Latest commit: 334cc6d

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

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[codecov]

Codecov Report

Merging #895 (334cc6d) into next-v1 (cd4f87c) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff            @@
##           next-v1     #895   +/-   ##
========================================
  Coverage    69.01%   69.01%           
========================================
  Files          205      205           
  Lines         2872     2872           
  Branches       791      791           
========================================
  Hits          1982     1982           
  Misses         775      775           
  Partials       115      115           

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[sungik-choi]

이슈 타이틀 영문 작성 안내에 대한 부분도 추가했습니다.