Add docblocks to ContentAPI and handleGuide

public/admin.php

@@ -1374,6 +1374,16 @@ function handleUsers(AdminAuth $auth, array $config): void
     require __DIR__ . '/../admin/templates/layout.php';
 }
 
+/**
+ * Render the admin guide page from a markdown file
+ *
+ * Reads the guide file for the selected language, renders it through
+ * CommonMark (with HeadingPermalink IDs moved to heading elements for
+ * working deep links), and outputs it via the admin layout.
+ *
+ * @param AdminAuth $auth Admin authentication instance
+ * @param array $config Site configuration
+ */
 function handleGuide(AdminAuth $auth, array $config): void
 {
     $user = $auth->getCurrentUser();