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

@@ -44,12 +44,12 @@ dataset_info:
   - name: topic
     dtype: string
   splits:
-  - name: test
-    num_bytes: 6607134
-    num_examples: 17705
   - name: train
     num_bytes: 17619123
     num_examples: 45640
+  - name: test
+    num_bytes: 6607134
+    num_examples: 17705
   - name: validation
     num_bytes: 1505979
     num_examples: 3926