docs: platform updates for api 21
docs: platform updates for api 21

Change-Id: I6dd1897641243a19ece0acfd16866cb0d7c3a24a

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