Add comment for config file

site/config/config.php

@@ -9,5 +9,5 @@
  */
 return [
     'debug' => true,
-    'yaml.handler' => 'symfony',
+    'yaml.handler' => 'symfony', // already makes use of the more modern Symfony YAML parser: https://getkirby.com/docs/reference/system/options/yaml (will become the default in a future Kirby version)
 ];