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

@@ -38,12 +38,12 @@ dataset_info:
           0: NONE
           1: ENTAILMENT
   splits:
-  - name: test
-    num_bytes: 339580
-    num_examples: 2448
   - name: train
     num_bytes: 864816
     num_examples: 6500
+  - name: test
+    num_bytes: 339580
+    num_examples: 2448
   - name: validation
     num_bytes: 66895
     num_examples: 500