Carlos Rogue enhanced the http4s/http4s repository by improving its documentation to support Mill as an alternative build tool for Scala projects. He introduced a Scala 2.x Mill giter8 template and added detailed Markdown instructions for initializing and running projects with Mill, addressing the needs of contributors who prefer it over sbt. His work focused on standardizing references to the Mill tool, clarifying naming conventions, and improving navigation through consistent cross-linking. By refining code blocks and examples, Carlos reduced onboarding friction and made the quickstart guide more accessible, demonstrating depth in documentation and a clear understanding of developer onboarding challenges.