Adding a JS version of the TS code snippet. (#18069)

Author: Oxyjun

src/content/docs/d1/get-started.mdx

@@ -13,6 +13,7 @@ import {
 	FileTree,
 	Tabs,
 	TabItem,
+	TypeScriptExample
 } from "~/components";
 
 This guide instructs you through:
@@ -298,6 +299,7 @@ After you have set up your database, run an SQL query from within your Worker.
 2. Clear the content of `index.ts`.
 3. Paste the following code snippet into your `index.ts` file:
 
+    <TypeScriptExample filename="index.ts">
     ```typescript
     export interface Env {
     	// If you set another name in wrangler.toml as the value for 'binding',
@@ -325,6 +327,7 @@ After you have set up your database, run an SQL query from within your Worker.
     	},
     } satisfies ExportedHandler<Env>;
     ```
+    </TypeScriptExample>
 
     In the code above, you: