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

@@ -27,12 +27,12 @@ dataset_info:
     sequence: string
   config_name: simplification
   splits:
-  - name: test
-    num_bytes: 396378
-    num_examples: 359
   - name: validation
     num_bytes: 2120187
     num_examples: 2000
+  - name: test
+    num_bytes: 396378
+    num_examples: 359
   download_size: 2443394
   dataset_size: 2516565
 ---