Merge "Add explanation about the purpose of accessibility heading and use case...

Merge "Add explanation about the purpose of accessibility heading and use case apps should consider." am: 407d5317 am: afc1b7d0 am: 08ae6de0 am: 389bce37 am: 8bd8e3ee

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/2151635



Change-Id: I6122eda7c5b6d4ed8d2da361d6cdaa13129ce12c
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>