Remove multiple navbar z-index callout

* Since we removed the z-index of our default navbars in 76baacf2, we no longer need this warning.
* A quick test of the new code showed no problems with dropdowns falling behind a sibling navbar, so folks should be good to go.

components.html

@@ -2025,10 +2025,6 @@ base_url: "../"
       <h4>Requires JavaScript</h4>
       <p>If JavaScript is disabled and the viewport is narrow enough that the navbar collapses, it will be impossible to expand the navbar and view the content within the <code>.navbar-collapse</code>.</p>
     </div>
-    <div class="bs-callout bs-callout-warning" id="multiple-navbars-warning">
-      <h4>Multiple navbars require custom code</h4>
-      <p>Multiple nearby navbars with dropdown menus are not supported by default. You will need to override the <code>z-index</code>es of the dropdown menus yourself. Otherwise, the dropdown menu will display behind the other navbar.</p>
-    </div>
 
     <div class="bs-example">
       <nav class="navbar navbar-default" role="navigation">