Document that the viewer pans to the initial pitch before starting auto rotation (see #744).

doc/json-config-parameters.md

@@ -52,7 +52,8 @@ counter-clockwise, and negative is clockwise.
 
 Sets the delay, in milliseconds, to start automatically rotating the panorama
 after user activity ceases. This parameter only has an effect if the
-`autoRotate` parameter is set.
+`autoRotate` parameter is set. Before starting rotation, the viewer is panned
+to the initial pitch.
 
 
 ### `autoRotateStopDelay` (number)

src/js/pannellum.js

@@ -2689,6 +2689,8 @@ this.setHorizonPitch = function(pitch) {
 
 /**
  * Start auto rotation.
+ *
+ * Before starting rotation, the viewer is panned to the initial pitch.
  * @memberof Viewer
  * @instance
  * @param {number} [speed] - Auto rotation speed / direction. If not specified, previous value is used.