style: use full CDC name

Author: sgratzl

themes/delphi/layouts/_default/coe.html

@@ -42,7 +42,7 @@ <h2>Supporters</h2>
       <div class="about-collaborator-special">
         <h3>Special thank to</h3>
         <ul>
-          <li>Center of Disease Control (CDC)</li>
+          <li>U.S. Centers for Disease Control and Prevention (US CDC)</li>
         </ul>
       </div>
     </div>