docs(v6): update JavaScript example for back-button

Author: soundproofboot

static/usage/v6/back-button/custom/index.md

@@ -1,6 +1,7 @@
 import Playground from '@site/src/components/global/Playground';
 
-import javascript from './javascript.md';
+import javascript_index_html from './javascript/index_html.md';
+import javascript_index_ts from './javascript/index_ts.md';
 
 import angular_example_component_html from './angular/example_component_html.md';
 import angular_example_component_ts from './angular/example_component_ts.md';
@@ -18,7 +19,12 @@ import vue_page_two from './vue/page_two_vue.md';
 <Playground
   version="6"
   code={{
-    javascript,
+    javascript: {
+      files: {
+        'index.html': javascript_index_html,
+        'index.ts': javascript_index_ts,
+      },
+    },
     angular: {
       files: {
         'src/app/example.component.html': angular_example_component_html,

static/usage/v6/back-button/custom/javascript.md renamed to static/usage/v6/back-button/custom/javascript/index_html.md

@@ -0,0 +1,29 @@
+```ts
+import { defineCustomElements } from '@ionic/core/loader';
+
+import { addIcons } from 'ionicons';
+import { caretBack } from 'ionicons/icons';
+
+/* Core CSS required for Ionic components to work properly */
+import '@ionic/core/css/core.css';
+
+/* Basic CSS for apps built with Ionic */
+import '@ionic/core/css/normalize.css';
+import '@ionic/core/css/structure.css';
+import '@ionic/core/css/typography.css';
+
+/* Optional CSS utils that can be commented out */
+import '@ionic/core/css/padding.css';
+import '@ionic/core/css/float-elements.css';
+import '@ionic/core/css/text-alignment.css';
+import '@ionic/core/css/text-transformation.css';
+import '@ionic/core/css/flex-utils.css';
+import '@ionic/core/css/display.css';
+
+/* Theme variables */
+import './theme/variables.css';
+
+addIcons({ caretBack });
+
+defineCustomElements();
+```