update nav titles to match homepage

Author: hmillersarah

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

@@ -39,11 +39,11 @@ <h4>IBM <b>IMS Central</b></h4>
                 <div>
                     <h3>Learn</h3>
                     <a href="ims-videos.html" tabindex="-1">
-                        <h5>IMS videos</h5>
+                        <h5>Videos</h5>
                         <p>Choose from hundreds of educational videos on IMS components, functions, and tools.</p>
                     </a>
                     <a href="ims-education.html" tabindex="-1">
-                        <h5>IMS courses</h5>
+                        <h5>Courses</h5>
                         <p>Get in-depth IMS education with these self-paced courses and instructor-led classes and earn digital badges.</p>
                     </a>
                     <a href="ims-repos.html" tabindex="-1">