docs: update popup menu provider example

lib/features/popup-menu/PopupMenuProvider.js

@@ -14,6 +14,32 @@ PopupMenuProvider.$inject = [ 'popupMenu' ];
 
 
 /**
+ * This method should implement the creation or update of a map of entry objects.
+ *
+ * @param {djs.model.Base} element
+ *
+ * The following example shows how to replace any entries returned 
+ * by previous providers with one entry which alerts the id of the current selected
+ * element, when clicking on the entry.
+ *
+ * @example
+ * PopupMenuProvider.getPopupMenuEntries = function(element) {
+ *   return function(entries) {
+ *     return {
+ *       alert: {
+ *         label: 'Alert element ID',
+ *         className: 'alert',
+ *         action: function () {
+ *         alert(element.id);
+ *       }
+ *     };
+ * };
+ */
+PopupMenuProvider.getPopupMenuEntries = function(element) {};
+
+
+/**
+ * @deprecated
  * This method should implement the creation of a list of entry objects.
  *
  * @param {djs.model.Base} element
@@ -33,7 +59,7 @@ PopupMenuProvider.$inject = [ 'popupMenu' ];
  *   }];
  *
  *  return entries;
- *}
+ * };
  */
 PopupMenuProvider.getEntries = function(element) {};
 
@@ -71,4 +97,4 @@ PopupMenuProvider.getHeaderEntries = function(element) {};
  *   this._popupMenu.registerProvider('my-provider-id', this);
  * }
  */
-PopupMenuProvider.register = function() {};
+PopupMenuProvider.register = function() {};