Add remark-toc plugin.

Add plugin for generating table of content automatically for markdown files.

astro.config.mjs

@@ -1,6 +1,7 @@
 import { defineConfig } from 'astro/config';
 import sitemap from "@astrojs/sitemap";
 import vue from "@astrojs/vue";
+import remarkToc from 'remark-toc';
 
 // https://astro.build/config
 export default defineConfig({
@@ -26,7 +27,10 @@ export default defineConfig({
       // Add custom transformers: https://shiki.style/guide/transformers
       // Find common transformers: https://shiki.style/packages/transformers
       transformers: []
-    }
+    },
+    remarkPlugins: [
+      [remarkToc, { heading: "(table[ -]of[ -])?contents?|toc|目录" }]
+    ],
   },
   site: 'https://lishouzhong.com',
   integrations: [