Youngjae Kim focused on enhancing developer experience in the line/abc-user-feedback repository by delivering clear, well-organized API and webhook documentation. Over two months, Youngjae used Markdown and documentation best practices to improve integration clarity, first by restructuring API documentation for easier navigation and direct access, then by adding a comprehensive table of webhook event types in GUIDE.md. These updates streamlined onboarding and reduced confusion for developers integrating with the ABC User Feedback service. The work demonstrated a methodical approach to documentation, emphasizing accessibility and maintainability, and addressed common integration pain points without introducing new features or fixing existing bugs.