Merge "Add a README to frameworks/base/config." am: ec2aafa614 am: 846984a499 am: 2616a44c26 am: 72da11e20b am: 6579c3be29

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1885634

Change-Id: Ib8b5889ee4534c69a3506f57351ecea62f839d1d