[CHANGE] add explanation field in question

Author: imdhruvgupta

app/models/question.js

@@ -3,6 +3,7 @@ import DS from "ember-data";
 export default DS.Model.extend({
   title: DS.attr(),
   description: DS.attr(),
+  explanation: DS.attr(),
   difficulty: DS.attr(),
   user: DS.belongsTo('user'),
   choices: DS.hasMany('choice'),

app/pods/components/question-editor/template.hbs

@@ -30,6 +30,18 @@
     </div>
   </div>
 
+  <div class="row justify-content-center align-items-center">
+    <div class="col-2">
+      <label>Question Explanation:</label>
+    </div>
+    <div class="col-5 input-group">
+      {{textarea type="text" class="input-text py-4" placeholder="Edit this explanation" value=question.explanation}}
+    </div>
+    <div class="col-5">
+      {{markdown-to-html question.explanation extensions='katex'}}
+    </div>
+  </div>
+
   {{#unless question.isNew}}
 
     <div class="button-dashed add-choice">