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

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



Change-Id: If08ab9af3186e37a8e59863ac701d3679e18bd36
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>