Worked on the mdn/content repository to enhance the accuracy of API documentation, focusing on clarifying the semantics of HTMLInputElement.selectionEnd. Addressed a documentation bug by specifying that selectionEnd represents the index immediately following the selection, ensuring alignment with actual browser behavior. This update, implemented using Markdown and technical writing skills, aimed to reduce developer confusion and lower support requests by providing precise, edition-aware documentation. The work emphasized traceable changes through detailed commit messages and cross-referencing related issues, contributing to improved onboarding for API users and maintaining high documentation standards within the project over the course of the month.