indicate that transformer_info might be more complex

architecture design proposal.md

@@ -134,7 +134,7 @@ A solution could be to define a transformer interface and let the transformers b
 ```php
 interface Transformer {
     public function get_supported_post_types(): array;
-    public function get_transformer_info(): string;
+    public function get_transformer_info(): array;
     public function to_object(WP_Post $post);
     ....
 }