docs: guide sitemap

Author: billyyyyy3320

docs/guide/getting-started.md

@@ -317,6 +317,25 @@ classification:
 
 - [Config > frontmatters](../config/README.md#frontmatters)
 
+## Sitemap
+
+I can't see a reason you don't want a sitemap. Sitemap is a XML file that helps search engines better index your blog.
+The file will be generated by simply passing down your host name as below. 
+```js
+// .vuepress/config.js
+module.exports = {
+  plugins: [
+    [
+      '@vuepress/blog',
+      {
+        sitemap: {
+          hostname: 'https://yourdomain'
+        },
+      },
+    ],
+  ],
+}
+```
 ## Comment
 
 Comment is a great way to make your blog much more lively. We integrate client side comment services: [Vssue](https://vssue.js.org/) and [Disqus](https://disqus.com/) in this plugin. The former is a vue-powered and issue-based open source project which can enable comments for your static pages, while the latter is a networked platform that provides comment service used by hundreds of thousands of websites.