Remove unnecessary </a> tag in Button element documentation page

Author: tiagoefmoraes

docs/documentation/elements/button.html

@@ -235,7 +235,6 @@
       <i class="fas fa-times"></i>
     </span>
   </button>
-  </a>
 </p>
 <p class="buttons">
   <button class="button is-small">