Update background.html

Minor typo and a few commas to break up the overly long sentence

src/_includes/accessibility/background.html

@@ -9,7 +9,7 @@
       The assistive technology may not find any content to read out to a user
     </li>
     <li>
-      The assistive technolog may read the unicode equivalent which could not match up to what the icon means in context or worse is just plain confusing
+      The assistive technology may read the unicode equivalent, which could not match up to what the icon means in context, or worse is just plain confusing
     </li>
   </ul>
 </div>