fix extension manager

docs/src/demos/Guide/BuildYourEditor/index.vue

@@ -55,15 +55,15 @@ export default {
     this.editor = new Editor({
       content: '<h2>Hey there!</h2><p>This editor is based on Prosemirror, fully extendable and renderless. You can easily add custom nodes as Vue components.</p>',
       extensions: [
-        new Document(),
-        new Paragraph(),
-        new Text(),
-        new CodeBlock(),
-        new History(),
-        new Bold(),
-        new Italic(),
-        new Code(),
-        new Heading(),
+        Document(),
+        Paragraph(),
+        Text(),
+        CodeBlock(),
+        History(),
+        Bold(),
+        Italic(),
+        Code(),
+        Heading(),
       ],
     })
   },