Merge "Add document for GSI specific packages" am: 0170eba510

Original change: https://android-review.googlesource.com/c/device/generic/common/+/2266746

Change-Id: Id1c17d93c2d88f3ab421697cb87131e187892205
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>