Add line highlight

packages/docusaurus-init/templates/classic/docs/tutorial-basics/create-a-document.md

@@ -28,7 +28,7 @@ Docusaurus automatically **creates a sidebar** from the `docs` folder.
 
 Add metadatas to customize the sidebar label and position:
 
-```md title="docs/hello.md"
+```md title="docs/hello.md" {1-4}
 ---
 sidebar_label: 'Hi!'
 sidebar_position: 3