[API] Restore JSDoc for openmct module

src/openmct.js

@@ -43,6 +43,15 @@ define([
     OverlayManager,
     ViewRegistry
 ) {
+
+    /**
+     * Open MCT is an extensible web application for building mission
+     * control user interfaces. This module is itself an instance of
+     * [MCT]{@link module:openmct.MCT}, which provides an interface for
+     * configuring and executing the application.
+     *
+     * @exports openmct
+     */
     var openmct = new MCT();
     var overlayManager = new OverlayManager(window.document.body);
     var actionRegistry = new Registry();