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

@@ -34,15 +34,15 @@ dataset_info:
     - name: answer_start
       dtype: int32
   splits:
-  - name: test
-    num_bytes: 1606931
-    num_examples: 1002
   - name: train
     num_bytes: 15508110
     num_examples: 10142
   - name: validation
     num_bytes: 5183809
     num_examples: 3219
+  - name: test
+    num_bytes: 1606931
+    num_examples: 1002
   download_size: 11508117
   dataset_size: 22298850
 ---