Update utilityFirst.html

Co-Authored-By: JehanKandy <jehankandy@gmail.com> Co-Authored-By: Vinura Pathirana <154809219+VinuraPathirana@users.noreply.github.com> Co-Authored-By: Anupa Gamage <125038143+anupa1998@users.noreply.github.com>

Author: 4 people

site/content/docs/utilityFirst.html

@@ -7,7 +7,10 @@
 <nav class="other-nav"> 
 </nav>
 
-hi all
+<div class="site-container">
+ <h1 class="jk-display-3">Utility-First CSS</h1> 
+</div>
+
 
 <footer class="footerbar">
 </footer>