Add mention that tabs should be <button> elements

per @mdo's suggestion

Author: patrickhlauke

site/content/docs/5.0/components/navs-tabs.md

@@ -308,7 +308,7 @@ Add dropdown menus with a little extra HTML and the [dropdowns JavaScript plugin
 
 Use the tab JavaScript plugin—include it individually or through the compiled `bootstrap.js` file—to extend our navigational tabs and pills to create tabbable panes of local content.
 
-Dynamic tabbed interfaces, as described in the [<abbr title="Web Accessibility Initiative">WAI</abbr> <abbr title="Accessible Rich Internet Applications">ARIA</abbr> Authoring Practices](https://www.w3.org/TR/wai-aria-practices/#tabpanel), require `role="tablist"`, `role="tab"`, `role="tabpanel"`, and additional `aria-` attributes in order to convey their structure, functionality and current state to users of assistive technologies (such as screen readers).
+Dynamic tabbed interfaces, as described in the [<abbr title="Web Accessibility Initiative">WAI</abbr> <abbr title="Accessible Rich Internet Applications">ARIA</abbr> Authoring Practices](https://www.w3.org/TR/wai-aria-practices/#tabpanel), require `role="tablist"`, `role="tab"`, `role="tabpanel"`, and additional `aria-` attributes in order to convey their structure, functionality and current state to users of assistive technologies (such as screen readers). As a best practice, we recommend using `<button>` elements for the tabs, as these are controls that trigger a dynamic change, rather than links that navigate to a new page or location.
 
 Note that dynamic tabbed interfaces should <em>not</em> contain dropdown menus, as this causes both usability and accessibility issues. From a usability perspective, the fact that the currently displayed tab's trigger element is not immediately visible (as it's inside the closed dropdown menu) can cause confusion. From an accessibility point of view, there is currently no sensible way to map this sort of construct to a standard WAI ARIA pattern, meaning that it cannot be easily made understandable to users of assistive technologies.