Update README for broadcast
Update README for broadcast

The commit 4e1490fe3070134e2200e0e8f936f718a9794959 replaced the service
by a broadcast receiver. Update the README accordingly.

WPO-Foundation/gnirehtet,Genymobile/gnirehtet,WPO-Foundation/gnirehtet,WPO-Foundation/gnirehtet,Genymobile/gnirehtet,Genymobile/gnirehtet,WPO-Foundation/gnirehtet