Update documentation for drawable state attributes
Update documentation for drawable state attributes

And you might ask yourself, what is this state_single? You might ask
yourself, how did it get here?

Change-Id: Ib7f95c2f8bd2028e2bf96281830755abdbcf0527

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