Added leafdoc comments for the 'zoomanim' event, fixes #2862

src/core/Events.leafdoc

@@ -113,4 +113,8 @@ The popup that was opened or closed.
 @property distance: Number
 The distance in pixels the draggable element was moved by.
 
-
+@miniclass ZoomAnimEvent (Event ojects)
+@inherits Event
+@property center: LatLng; The current center of the map
+@property zoom: Number; The current zoom level of the map
+@property noUpdate: Boolean; Whether layers should update their contents due to this event

src/map/anim/Map.ZoomAnimation.js

@@ -107,6 +107,8 @@ L.Map.include(!zoomAnimated ? {} : {
 			L.DomUtil.addClass(this._mapPane, 'leaflet-zoom-anim');
 		}
 
+		// @event zoomanim: ZoomAnimEvent
+		// Fired on every frame of a zoom animation
 		this.fire('zoomanim', {
 			center: center,
 			zoom: zoom,