docs: fix typo

Author: brc-dd

Diff for: docs/guide/markdown.md

@@ -587,7 +587,7 @@ It also supports [line highlighting](#line-highlighting-in-code-blocks):
 
 **Output**
 
-<<< @/snippets/snippet.js
+<<< @/snippets/snippet.js{2}
 
 ::: tip
 The value of `@` corresponds to the source root. By default it's the VitePress project root, unless `srcDir` is configured. Alternatively, you can also import from relative paths:

Diff for: docs/zh/guide/markdown.md

@@ -593,7 +593,7 @@ const line4 = 'This is line 4'
 
 **输出**
 
-<<< @/snippets/snippet.js
+<<< @/snippets/snippet.js{2}
 
 ::: tip
 `@` 的值对应于源代码根目录，默认情况下是 VitePress 项目根目录，除非配置了 `srcDir`。或者也可以从相对路径导入：