Add docstring for _use_dict_result

Author: sfc-gh-pczajka

src/snowflake/connector/cursor.py

@@ -432,6 +432,7 @@ def __del__(self) -> None:  # pragma: no cover
     @property
     @abc.abstractmethod
     def _use_dict_result(self) -> bool: ...
+        """Decides whether results from helper functions are returned as a dict."""
 
     @property
     def description(self) -> list[ResultMetadata]: