update preview version number to 2 for offline docs
update preview version number to 2 for offline docs

Change-Id: I56cab8d21f9521fab17ec79a441c518cf9da536c

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