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

Merge "Add details about theme stability" into sc-dev am: 9aff8397 am: 2a1b040e am: a3c84daa am: 18f9966a

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

Change-Id: I30b27d8528cdf67e6c3a8fff36c29d4f4dbc1ea2