fix scrollSpy instructions for JS call

Don't really know if this is correct, but at least it only worked for me that way...

javascript.html

@@ -531,7 +531,7 @@ $('.dropdown-toggle').dropdown()
     <h3>Via JavaScript</h3>
     <p>Call the scrollspy via JavaScript:</p>
 {% highlight js %}
-$('#navbar-example').scrollspy(options)
+$('body').scrollspy({ target: '#navbar-example' )
 {% endhighlight %}
 
     <div class="bs-callout bs-callout-danger">