Javascript docs: Accessibility and cosmetic changes to headings.

Closes #15915 by merging it.

docs/_includes/js/scrollspy.html

@@ -94,7 +94,7 @@ $('body').scrollspy({ target: '#navbar-example' })
 
 
   <h3 id="scrollspy-methods">Methods</h3>
-  <h4>.scrollspy('refresh')</h4>
+  <h4><code>.scrollspy('refresh')</code></h4>
   <p>When using scrollspy in conjunction with adding or removing of elements from the DOM, you'll need to call the refresh method like so:</p>
 {% highlight js %}
 $('[data-spy="scroll"]').each(function () {