Studio Section Highlights: add doc and preview text to modal

cms/static/js/models/xblock_info.js

@@ -163,8 +163,10 @@ function(Backbone, _, str, ModuleUtils) {
             /**
              * This xBlock's Highlights to message to learners.
              */
-            highlights: null,
-            highlights_enabled: null
+            highlights: [],
+            highlights_enabled: false,
+            highlights_preview_only: true,
+            highlights_doc_url: ''
         },
 
         initialize: function() {

cms/static/js/views/modals/course_outline_modals.js

@@ -236,12 +236,7 @@ define(['jquery', 'backbone', 'underscore', 'gettext', 'js/views/baseview',
         },
 
         getIntroductionMessage: function() {
-            return StringUtils.interpolate(
-                gettext(
-                  'Enter 3-5 highlights to include in the email message that learners receive for ' +
-                  'this section (250 character limit).'
-                )
-            );
+            return '';
         },
 
         callAnalytics: function(event) {
@@ -930,7 +925,9 @@ define(['jquery', 'backbone', 'underscore', 'gettext', 'js/views/baseview',
                 {},
                 AbstractEditor.prototype.getContext.call(this),
                 {
-                    highlights: this.model.get('highlights') || []
+                    highlights: this.model.get('highlights'),
+                    highlights_preview_only: this.model.get('highlights_preview_only'),
+                    highlights_doc_url: this.model.get('highlights_doc_url')
                 }
             );
         }

cms/static/sass/views/_outline.scss

@@ -671,6 +671,10 @@
     .highlight-input-label {
       font-weight: 600;
     }
+
+    .highlights-info {
+      font-size: smaller;
+    }
   }
 
   // outline: edit item settings