GPU.md: document setting up the GPU inside docker
GPU.md: document setting up the GPU inside docker

Signed-off-by: Iliyan Malchev <b9962a40c76f189681da2829a74a26cab77021ea@google.com>

google/android-cuttlefish,google/android-cuttlefish,google/android-cuttlefish,google/android-cuttlefish,google/android-cuttlefish,google/android-cuttlefish,google/android-cuttlefish