Add documentation for the PRAMIN aperture mechanism used by nova-core for direct VRAM access. Nova only uses TARGET=VRAM for VRAM access. The SYS_MEM target values are documented for completeness but not used by the driver. Signed-off-by: Joel Fernandes <joelagnelf@nvidia.com> [ecourtney: fix the TARGET encodings, KiB/MiB units, wording nits] [ecourtney: wrap at 80 columns] Signed-off-by: Eliot Courtney <ecourtney@nvidia.com> Acked-by: Danilo Krummrich <dakr@kernel.org> Link: https://patch.msgid.link/20260827-pramin-split-v3-7-24b24d7afc52@nvidia.com Signed-off-by: Alexandre Courbot <acourbot@nvidia.com>