Merge "Update documentation for Image to be clear on valid format enums." into tm-dev am: 82409626b9

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17006063

Change-Id: I04ae4cece1fcbac12d7391ce5219408a090e3689
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>