add placeholder markup to example block editor file

web/app/themes/badegg/resources/views/blocks/example/index.jsx

@@ -1,17 +1,22 @@
 // block.json's editorScript, loaded only in the block editor
 
+import metadata from './block.json';
 import { registerBlockType } from '@wordpress/blocks';
 import { useBlockProps } from '@wordpress/block-editor';
-import metadata from './block.json';
+import { containerClassNames, sectionClassNames } from '../../../js/blocks/lib/classNames';
 
 registerBlockType(metadata.name, {
-  edit() {
+  edit({ attributes }) {
     const blockProps = useBlockProps();
 
+    blockProps.className = sectionClassNames(attributes, blockProps.className, ['bg-success', 'knockout']).join(' ');
+
     return (
-      <section { ...blockProps }>
-        <h2>Bad Egg Block Example</h2>
-      </section>
+      <div { ...blockProps }>
+        <div className="container align-center wysiwyg">
+          <h2>Bad Egg Block Example</h2>
+        </div>
+      </div>
     );
   }
 });