docs: Release notes for support lib v20
docs: Release notes for support lib v20

Change-Id: I82bbad9ad8945e9437b790e0f47622ef00b318f1

xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base,xorware/android_frameworks_base