Better document which events are fired

The map does not fire ol.render.Event#render. Change events are
now only listed for classes that fire them, and a description
about when they are fired is added.

src/ol/geolocation.js

@@ -51,6 +51,7 @@ ol.GeolocationProperty = {
  *
  * @constructor
  * @extends {ol.Object}
+ * @fires change Triggered when the position changes.
  * @param {olx.GeolocationOptions=} opt_options Options.
  * @todo api
  */