tfds download_and_prepare: log config being used.

PiperOrigin-RevId: 238082394

Author: pierrot0

tensorflow_datasets/scripts/download_and_prepare.py

@@ -136,6 +136,7 @@ def main(_):
       raise ValueError(
           "--builder_config_id can only be used with datasets with configs")
     config = builder.BUILDER_CONFIGS[FLAGS.builder_config_id]
+    logging.info("Running download_and_prepare for config: %s", config.name)
     builder_for_config = tfds.builder(
         builder.name, data_dir=FLAGS.data_dir, config=config)
     download_and_prepare(builder_for_config)