add llms.txt to build output (#1289)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

Author: rezrah

apps/next-docs/app/llms.txt/route.ts

@@ -0,0 +1,11 @@
+import {generateLLMsTxt} from '@primer/doctocat-nextjs/llms'
+
+export const dynamic = 'force-static'
+
+export async function GET() {
+  const content = await generateLLMsTxt()
+
+  return new Response(content, {
+    headers: {'Content-Type': 'text/plain; charset=utf-8'},
+  })
+}

apps/next-docs/content/index.mdx

@@ -1,7 +1,7 @@
 ---
 title: Homepage
-description: That
-keywords: test, test2
+description: Documentation for Primer Brand - GitHub's design system for brand-led marketing experiences
+keywords: ['home']
 layout: custom
 ---
 

apps/next-docs/next-env.d.ts

@@ -1,6 +1,6 @@
 /// <reference types="next" />
 /// <reference types="next/image-types/global" />
-/// <reference path="./.next/types/routes.d.ts" />
+import "./.next/types/routes.d.ts";
 
 // NOTE: This file should not be edited
 // see https://nextjs.org/docs/app/api-reference/config/typescript for more information.