feat: support mermaid code blocks in Markdown (#7490)

Co-authored-by: Joshua Chen <sidachen2003@gmail.com>
Co-authored-by: sebastienlorber <lorber.sebastien@gmail.com>

website/docusaurus.config.js

@@ -118,6 +118,9 @@ const config = {
       },
     }),
   },
+  markdown: {
+    mermaid: true,
+  },
   onBrokenLinks: 'throw',
   onBrokenMarkdownLinks: 'warn',
   favicon: 'img/docusaurus.ico',
@@ -280,6 +283,7 @@ const config = {
         ],
       },
     ],
+    '@docusaurus/theme-mermaid',
     ...dogfoodingPluginInstances,
   ],
   presets: [