Add docs for how to change default JS plugin settings

Closes #14250.

docs/_includes/js/overview.html

@@ -47,6 +47,12 @@ $('#myModal').modal('show')                // initializes and invokes show immed
 
   <p>Each plugin also exposes its raw constructor on a <code>Constructor</code> property: <code>$.fn.popover.Constructor</code>. If you'd like to get a particular plugin instance, retrieve it directly from an element: <code>$('[rel="popover"]').data('popover')</code>.</p>
 
+  <h4>Default settings</h4>
+  <p>You can change the default settings for a plugin by modifying the plugin's <code>Constructor.DEFAULTS</code> object:<p>
+{% highlight js %}
+$.fn.modal.Constructor.DEFAULTS.keyboard = false // changes default for the modal plugin's `keyboard` option to false
+{% endhighlight %}
+
   <h3 id="js-noconflict">No conflict</h3>
   <p>Sometimes it is necessary to use Bootstrap plugins with other UI frameworks. In these circumstances, namespace collisions can occasionally occur. If this happens, you may call <code>.noConflict</code> on the plugin you wish to revert the value of.</p>
 {% highlight js %}