Added total time of a course, marking chapters and courses to sync offline.

app/Models/Chapter.php

@@ -14,6 +14,7 @@ use Illuminate\Database\Eloquent\Relations\BelongsTo;
  * @property string $title
  * @property string $duration
  * @property integer $course_id
+ * @property bool $sync_offline
  */
 class Chapter extends Model
 {
@@ -27,6 +28,7 @@ class Chapter extends Model
         'title',
         'duration',
         'course_id',
+        'sync_offline',
     ];
 
     public function course(): BelongsTo