config.yaml is a format for defining custom AI code agents. An agent has some top-level properties (e.g. name, version), but otherwise consists of composable lists of blocks such as models and rules, which are the atomic building blocks of an agent.
The config.yaml is parsed by the open-source Continue IDE extensions to create custom agent experiences. When you log in to hub.continue.dev, your agents will automatically be synced with the IDE extensions.