Add doc note to _.defaults for a deep version. [ci skip] [closes #154]

lodash.js

@@ -5726,6 +5726,9 @@
      * object for all destination properties that resolve to `undefined`. Once a
      * property is set, additional defaults of the same property will be ignored.
      *
+     * Note: See the [documentation example of `_.partialRight`](http://lodash.com/docs#partialRight)
+     * for a deep version of this method.
+     *
      * @static
      * @memberOf _
      * @category Objects