Building on what Highorse said up above. In a high angle of attack, low speed, single engine configuration, the thrustline for both engines, due to P factor is on the right side of the nacelle. The amount of yaw caused by these displaced thrustlines is the moment caused by the thrust and the straight line distance from the CG to the centerline of thrust. If we bend that thrusline in by canting the nacelles outward you shorten the distance from the CG to the thrustline thus reducing the yawing moment. The extreme example of this is the JU-87 two outboard engines.