fix(ssr): use absolute href for alternate rss link (#9794)

Author: caugner

Diff for: ssr/render.ts

@@ -263,7 +263,7 @@ export default function render(
       ? "noindex, nofollow"
       : "index, follow";
   const robotsMeta = `<meta name="robots" content="${robotsContent}">`;
-  const rssLink = `<link rel="alternate" type="application/rss+xml" title="MDN Blog RSS Feed" href="/${DEFAULT_LOCALE}/blog/rss.xml" hreflang="en" />`;
+  const rssLink = `<link rel="alternate" type="application/rss+xml" title="MDN Blog RSS Feed" href="${BASE_URL}/${DEFAULT_LOCALE}/blog/rss.xml" hreflang="en" />`;
   const ssr_data = [...translations, ...webfontTags, rssLink, robotsMeta];
   let html = buildHtml;
   html = html.replace(