Contributed to the Lumi-supercomputer/lumi-userguide repository by enhancing documentation for Singularity container usage, with a focus on clarifying PRoot-based build options. The work involved revising and expanding the Containers documentation page to provide clearer guidance and practical examples, aiming to streamline developer onboarding and improve user understanding of containerization workflows. Emphasizing technical writing and documentation skills, the developer utilized Markdown to ensure readability and reduce ambiguity in deployment instructions. The update addressed common pain points in container build processes, offering detailed explanations that support both new and experienced users working with Singularity and PRoot within the Lumi supercomputing environment.