add docs note about browsers w/ JS disabled; fixes #14134

[skip sauce]

docs/_includes/js/overview.html

@@ -64,6 +64,9 @@ $('#myModal').on('show.bs.modal', function (e) {
 })
 {% endhighlight %}
 
+  <h3 id="js-disabled">No special fallbacks when JavaScript is disabled</h3>
+  <p>Bootstrap's plugins don't fall back particularly gracefully when JavaScript is disabled. If you care about the user experience in this case, use <a href="https://developer.mozilla.org/en-US/docs/Web/HTML/Element/noscript"><code>&lt;noscript&gt;</code></a> to explain the situation (and how to re-enable JavaScript) to your users, and/or add your own custom fallbacks.</p>
+
   <div class="bs-callout bs-callout-warning" id="callout-third-party-libs">
     <h4>Third-party libraries</h4>
     <p><strong>Bootstrap does not officially support third-party JavaScript libraries</strong> like Prototype or jQuery UI. Despite <code>.noConflict</code> and namespaced events, there may be compatibility problems that you need to fix on your own.</p>

docs/_includes/nav/javascript.html

@@ -6,6 +6,7 @@
     <li><a href="#js-programmatic-api">Programmatic API</a></li>
     <li><a href="#js-noconflict">No conflict</a></li>
     <li><a href="#js-events">Events</a></li>
+    <li><a href="#js-disabled">When JavaScript is disabled</a></li>
     <li><a href="#callout-third-party-libs">Third-party libraries</a></li>
   </ul>
 </li>