added next-sitemap config

Author: theRuslan

next-sitemap.js

@@ -0,0 +1,9 @@
+/** @type {import('next-sitemap').IConfig} */
+
+module.exports = {
+  siteUrl: process.env.SITE_URL || "https://domain.com",
+  changefreq: "daily",
+  priority: 0.7,
+  sitemapSize: 5000,
+  generateRobotsTxt: true,
+};