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

@@ -39,12 +39,12 @@ dataset_info:
     dtype: string
   config_name: ohsumed
   splits:
-  - name: test
-    num_bytes: 338533901
-    num_examples: 293855
   - name: train
     num_bytes: 60117860
     num_examples: 54709
+  - name: test
+    num_bytes: 338533901
+    num_examples: 293855
   download_size: 139454017
   dataset_size: 398651761
 ---