Update techniques/html/H4.html

Author: patrickhlauke

techniques/html/H4.html

@@ -17,7 +17,7 @@
             <code>0</code> and <code>32767</code>. </p>
       <p>When the interactive elements are navigated using the tab key, the elements are given
             focus in increasing order of the value of their <code>tabindex</code> attribute.
-            Elements that have a <code>tabindex</code> value higher than zero will receive focus
+            Elements that have a <code>tabindex</code> value higher than <code>0</code> will receive focus
             before elements without a <code>tabindex</code> or a <code>tabindex</code> of 0. After
             all of the elements with a tabindex higher than 0 have received focus, the rest of the
             interactive elements are given focus in the order in which they appear in the web