preserve hardcoded markdown content in TOC files

layouts/generic-toc.html

@@ -45,6 +45,8 @@
           {% include featured-links %}
           {% endif %}
 
+          {{ renderedPage }}
+
           {% include generic-toc-items %}
         </div>
         </div>

script/content-migrations/update-tocs.js

@@ -73,7 +73,7 @@ indexFiles
     }
 
     // Index files should no longer have body content, so we write an empty string
-    fs.writeFileSync(indexFile, frontmatter.stringify('', data, { lineWidth: 10000 }))
+    fs.writeFileSync(indexFile, frontmatter.stringify(content, data, { lineWidth: 10000 }))
   })
 
 function getLinks (linkItemArray) {