[dagster-iceberg] Fix indentation of docstring

Author: cmpadden

libraries/dagster-iceberg/src/dagster_iceberg/io_manager/base.py

@@ -182,6 +182,7 @@ def my_table_a(my_table: pa.Table):
         Valid modes are ``append`` and ``overwrite``; default is ``overwrite``.
 
         .. code-block:: python
+
             # set at definition time via definition metadata
             @asset(
                 metadata={"write_mode": "append"}