Clean up the introduction where the notification mechanism is defined so that it becomes more clear what its usage is and what the attributes of an engine are that provide these capabilities. Change-Id: I4eeb9029b17d562111371c6f5155570b7a31859c
Clean up the introduction where the notification mechanism is defined so that it becomes more clear what its usage is and what the attributes of an engine are that provide these capabilities. Change-Id: I4eeb9029b17d562111371c6f5155570b7a31859c