Merge "Add AuthMgr README" into main am: 91a7beb65d

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/3492770

Change-Id: Ia56a700b1184a084ff33ef73ffcad0d50f003ee7
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>