Add comment markers for live documentation

Reviewed By: passy

Differential Revision: D21998029

fbshipit-source-id: 9eb563dedd2a13de0b4b9798e529c4ad3293560a

website/docusaurus.config.js

@@ -84,7 +84,9 @@ const siteConfig = {
     '/js/google-analytics.js',
   ],
   stylesheets: [],
+  // start_config_example
   plugins: [require.resolve('docusaurus-plugin-internaldocs-fb')],
+  // end_config_example
   presets: [
     [
       '@docusaurus/preset-classic',