Add robots.txt and sitemap info to build

public/robots.txt

@@ -0,0 +1,4 @@
+User-agent: *
+Allow: /
+
+Sitemap: https://blog.cassidoo.co/sitemap-index.xml

src/components/BaseHead.astro

@@ -52,6 +52,9 @@ const { title, description, image = "/home-blog-card.png" } = Astro.props;
 		title={SITE_TITLE}
 	/>
 
+	<!-- Sitemap -->
+	<link rel="sitemap" href="/sitemap-index.xml" />
+
 	<!-- Google Search Console -->
 	<meta name="google-site-verification" content="4G1fPeskmgxlQRWUoJxDlkDxL0VswExwh1MuRAwkQzg" />