Merge "Add details about theme stability" into sc-dev am: 9aff8397 am:...

Merge "Add details about theme stability" into sc-dev am: 9aff8397 am: a35809b1 am: 9b578bf0 am: f81aaca8

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/16176790

Change-Id: I4f275be65376cfb75bb18000cf8d2dfcfde1fe56