Add README with details about the status of support for this app am: c16f2d9123

Original change: https://android-review.googlesource.com/c/platform/packages/apps/Car/DebuggingRestrictionController/+/3320773

Change-Id: I336fd4f4adbd4f0673e26f0e71d47368d85a5d64
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>