start work on challenge model but getting an error; add all project euler challenges

models/Course.js

@@ -11,9 +11,7 @@ var courseSchema = new mongoose.Schema({
     link: String,
     image: String,
     time: Number,
-    directions_1: String,
-    directions_2: String,
-    directions_3: String,
+    directions: Array
 });
 
 var Courses = module.exports = mongoose.model('Course', courseSchema);