docs: add discord server widget and search

Author: buehler

docs/docusaurus.config.js

@@ -44,7 +44,18 @@ const config = {
     mermaid: true,
   },
 
-  themes: ["@docusaurus/theme-mermaid"],
+  themes: [
+    "@docusaurus/theme-mermaid",
+    [
+      require.resolve("@easyops-cn/docusaurus-search-local"),
+      /** @type {import("@easyops-cn/docusaurus-search-local").PluginOptions} */
+      ({
+        hashed: true,
+        language: ["en"],
+        indexPages: true,
+      }),
+    ],
+  ],
 
   themeConfig: {
     image: "img/logo_big.png",