feat(config): add title, description and seo metas

Signed-off-by: iverly <github@iverly.net>

theme.config.tsx

@@ -1,4 +1,5 @@
-import type { DocsThemeConfig } from 'nextra-theme-docs';
+import { useRouter } from 'next/router';
+import { useConfig, type DocsThemeConfig } from 'nextra-theme-docs';
 import React from 'react';
 
 const config: DocsThemeConfig = {
@@ -7,6 +8,50 @@ const config: DocsThemeConfig = {
   project: {
     link: 'https://github.com/faast-rt',
   },
+  head: () => {
+    const { asPath, defaultLocale, locale } = useRouter();
+    const { frontMatter } = useConfig();
+
+    const domain = 'faast-rt.com';
+    const url =
+      'https://faast-rt.com' +
+      (defaultLocale === locale ? asPath : `/${locale}${asPath}`);
+
+    return (
+      <>
+        <meta property="og:url" content={url} />
+        <meta property="og:type" content="website" />
+        <meta
+          property="og:title"
+          content={frontMatter.title || 'Faast - A Serverless runtime in Rust'}
+        />
+        <meta
+          property="og:description"
+          content={frontMatter.description || 'A Serverless runtime in Rust'}
+        />
+
+        <meta name="twitter:card" content="summary_large_image" />
+        <meta property="twitter:domain" content={domain} />
+        <meta property="twitter:url" content={url} />
+        <meta
+          name="twitter:title"
+          content={frontMatter.title || 'Faast - A Serverless runtime in Rust'}
+        />
+        <meta
+          name="twitter:description"
+          content={frontMatter.description || 'A Serverless runtime in Rust'}
+        />
+      </>
+    );
+  },
+  useNextSeoProps() {
+    const { asPath } = useRouter();
+    if (asPath !== '/') {
+      return {
+        titleTemplate: '%s - Faast',
+      };
+    }
+  },
 };
 
 export default config;