Fix typo in error_code_list.rst (python#17645)

Author: sobolevn

docs/source/error_code_list.rst

@@ -1184,7 +1184,7 @@ comment:
 
 .. code-block:: python
 
- class MyClass
+ class MyClass:
  @special # type: ignore[prop-decorator]
  @property
  def magic(self) -> str: