Conceptual overview of the steps involved with integrating CodeRabbit with any supported Git platform. List the supported platforms, and outline the common setup steps. Lead the reader to the platform-specific next page. Part of the [Improved CodeRabbit setup guides and configuration reference](https://docs.google.com/document/d/1GUhv-FiTq_Ee-aKXLUPdodIJVR-PhMs0Q_rUWjCqoGc/edit?usp=sharing) content plan.