[PATCH 7/9] docs: driver-api: Add Surface Aggregator subsystem documentation

Add documentation for the Surface Aggregator subsystem and its client drivers, giving an overview of the subsystem, its use-cases, its internal structure and internal API, as well as its external API for writing client drivers. Signed-off-by: Maximilian Luz --- Changes from RFC: - change SPDX

[RFC PATCH 7/9] docs: driver-api: Add Surface Aggregator subsystem documentation

Add documentation for the Surface Aggregator subsystem and its client drivers, giving an overview of the subsystem, its use-cases, its internal structure and internal API, as well as its external API for writing client drivers. Signed-off-by: Maximilian Luz ---