We've recently moved some of the REST API documentation. If you can't find what you're looking for, you might try the new Branches, Collaborators, Commits, Deploy Keys, Deployments, GitHub Pages, Releases, Metrics, Webhooks REST API pages.
コラボレーター
REST API を使うと、リポジトリでコラボレーターの追加、招待、削除を行うことができます。