Merge "Document fullScreenIntent requires IMPORTANCE_HIGH" into tm-qpr-dev am: a9a1ba19c7 am: fdfc0d81d6

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/20069356

Change-Id: I71954f13cd18f3240b6eaae9a7e19b3306f27273
Signed-off-by: Automerger Merge Worker <[email protected]>