Camera: Improve docs for session parameters am: 622e3bd686 am: 46248c9939 am: 33252d008b

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/av/+/24621696

Change-Id: I76747e9f548cc431715731eaba194500dd229201
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>