Doc update: clarify rules for rate param
Doc update: clarify rules for rate param

"Bug: 5581113"

Change-Id: Ic87f1c331fba2b08de295b2d77832739bf823500

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