DocBlock added for the 'container' option

Author: vovayatsyuk

lib/web/mage/sticky.js

@@ -11,6 +11,12 @@ define([
 
     $.widget('mage.sticky', {
         options: {
+            /**
+             * Element selector, who's height that will be used to restrict the
+             * maximum offsetTop position of the stuck element.
+             * Default uses document body.
+             * @type {String}
+             */
             container: '',
 
             /**