docs: update reference to unplugin-icons (#74)

Author: D3SOX

guide/syntax.md

@@ -219,7 +219,7 @@ This is another note
 
 ## Icons
 
-Slidev allows you to have the accessing to almost all the popular open-source iconsets **directly** in your markdown. Powered by [`vite-plugin-icons`](https://github.com/antfu/vite-plugin-icons) and [Iconify](https://iconify.design/).
+Slidev allows you to have the accessing to almost all the popular open-source iconsets **directly** in your markdown. Powered by [`unplugin-icons`](https://github.com/antfu/unplugin-icons) and [Iconify](https://iconify.design/).
 
 The naming follows [Iconify](https://iconify.design/)'s conversion `{collection-name}-{icon-name}`. For example: