Merge "Camera: Improve documentation for 3A regions" into tm-dev am: 3a7a59da am: c04e7d8b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/17450690



Change-Id: I4a86a83d2f0c845df8f2a7ea4f88788160253419
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>