A GitHub repository has become the preferred place to manage OpenAPI and other artifacts, and APIs.json contracts just bring more order to this already growing approach to using source control as the factor floor for API operations.
GitHub provides all the controls you will need to manage API contracts and all the human and machine-readable properties, building on top of Git, and all the teams, issues, and other resources that come default with a repository. Whether public or private, a GitHub repository is an excellent place to coordinate around the development of an API.
APIs require a single source of truth across the API lifecycle, and GitHub provides this out of the box, providing a place where product and engineering stakeholders can collaborate and communicate around all the stages of the lifecycle for an API. Don’t worry about making it too elaborate, just make sure there is a single source of truth for everything that occurs around your API.