Fix ruby-parse example

Without `--legacy`, it would return `kwargs`, not `hash`:

    (send
      (const nil :Comment) :new
      (kwargs
        (pair
          (sym :user)
          (send nil :current_user))))

docs/modules/ROOT/pages/node_pattern.adoc

@@ -477,7 +477,7 @@ current symbol is being called from an initialization method, like:
 
 [source,sh]
 ----
-$ ruby-parse -e 'Comment.new(user: current_user)'
+$ ruby-parse --legacy -e 'Comment.new(user: current_user)'
 (send
   (const nil :Comment) :new
   (hash