update nav with arcade page

Author: hmillersarah

web-components/nav-header/nav-header.html

@@ -81,9 +81,9 @@ <h5>Courses</h5>
             </p>
           </a>
           <a href="ims-arcade.html" tabindex="-1">
-            <h5>Arcade</h5>
+            <h5>IMS arcade</h5>
             <p>
-              Test your IMS knowledge and learn about the latest IMS topics.
+              Test your IMS knowledge and have some fun with a few quick games.
             </p>
           </a>
           <a href="ims-repos.html" tabindex="-1">