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

@@ -34,12 +34,12 @@ dataset_info:
           0: negative
           1: positive
   splits:
-  - name: test
-    num_bytes: 6837430
-    num_examples: 11005
   - name: train
     num_bytes: 8367687
     num_examples: 17941
+  - name: test
+    num_bytes: 6837430
+    num_examples: 11005
   download_size: 14700057
   dataset_size: 15205117
 ---