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

@@ -44,15 +44,15 @@ dataset_info:
     sequence: string
   config_name: plain_text
   splits:
-  - name: test
-    num_bytes: 884784
-    num_examples: 1924
   - name: train
     num_bytes: 7114730
     num_examples: 15383
   - name: validation
     num_bytes: 884940
     num_examples: 1922
+  - name: test
+    num_bytes: 884784
+    num_examples: 1924
   download_size: 12848091
   dataset_size: 8884454
 ---