Update input_objects.md

- Adding the real output of `attributes.full_text` to make it even more clear.

Author: Pradyumna Shembekar

guides/type_definitions/input_objects.md

@@ -73,10 +73,10 @@ def create_post(attributes:)
   # => "Types::PostAttributes"
   # Access a value by method (underscore-cased):
   puts attributes.full_text
-  # => "..."
+  # => "This is my first post"
   # Or by hash-style lookup (camel-cased, for compatibility):
   puts attributes[:fullText]
-  # => "..."
+  # => "This is my first post"
 end
 ```