feat: add mermaid theme support and enable mermaid in markdown

Author: veithly

docusaurus.config.ts

@@ -17,6 +17,12 @@ const config: Config = {
 
   plugins: [tailwindPlugin],
 
+  themes: ['@docusaurus/theme-mermaid'],
+
+  markdown: {
+    mermaid: true,
+  },
+
   // Set the production url of your site here
   url: 'https://xspoonai.github.io',
   // Set the /<baseUrl>/ pathname under which your site is served