docs: add static search support for documentation site

docs/app/[lang]/api/search/route.ts

@@ -0,0 +1,13 @@
+import { createFromSource } from 'fumadocs-core/search/server';
+import { source } from '@/lib/source';
+
+export const revalidate = false;
+export const { staticGET: GET } = createFromSource(source, {
+  localeMap: {
+    cn: { language: 'english' },
+  },
+});
+
+export function generateStaticParams() {
+  return [{ lang: 'en' }, { lang: 'cn' }];
+}