Fix button style in popover demo.

Author: knadh

docs/content/components/dropdown.md

@@ -44,7 +44,7 @@ Wrap in `<ot-dropdown>`. Use `popovertarget` on the trigger and `popover` on the
     </header>
     <br />
     <footer>
-      <button class="outline" class="small" popovertarget="demo-confirm">Cancel</button>
+      <button class="outline small" popovertarget="demo-confirm">Cancel</button>
       <button data-variant="danger" class="small" popovertarget="demo-confirm">Delete</button>
     </footer>
   </article>