Reorder split names

Reorder split names in the YAML metadata to be aligned with the order in the loading script.
See: https://github.com/huggingface/datasets/issues/5258

README.md

@@ -55,10 +55,10 @@ dataset_info:
           0: '0'
           1: '1'
   splits:
-  - name: test
+  - name: train
     num_bytes: 428553
     num_examples: 4015
-  - name: train
+  - name: test
     num_bytes: 428553
     num_examples: 4015
   - name: validation