Kostas Vilkelis overhauled the ADA HPC cluster documentation for the ubvu/open-handbook repository, focusing on improving onboarding and user guidance for cluster users. He consolidated and reorganized content related to software access, login procedures, SLURM job scheduling, hardware details, Open OnDemand, and help resources, resulting in a more navigable and user-friendly documentation structure. Using Markdown and Shell scripting, Kostas applied disciplined editorial fixes to enhance consistency, clarity, and usability, including improved headers and login instructions. The work culminated in a comprehensive first draft with author attribution, reflecting a methodical approach to technical writing and documentation in the HPC domain.