docs: add additional stories

• docs: add story for jumbotron
• docs: add dropdown navbar
• docs: add story for direct nav
• docs: add story for promotion widget
• docs: add story for working group list widget

.storybook/preview-body.html

 <div id="storybook-root-wrapper">
-  <div class="container" id="storybook-root">
-    
-  </div>
 </div>
 <div 
   class="wip-disclaimer alert alert-warning"