[PATCH 2/2] drm/doc: Document that userspace should utilize CRTCs bottom up

[Simon Ser]

Sorry for the huge delay. Generally this looks good but maybe we
could explain a bit more what "bottom up" means exactly since it
may not be super obvious.

Maybe something among these lines?

    Bottom up means that the first CRTCs in the array should be used
    first. For instance, if the driver exposes 4 CRTCs and user-space
    needs 2, it should prioritize CRTCs with indices 0 and 1.