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

@@ -68,12 +68,12 @@ dataset_info:
   - name: test
     num_bytes: 32234761
     num_examples: 15878
-  - name: train
-    num_bytes: 107345917
-    num_examples: 56355
   - name: validation
     num_bytes: 15159314
     num_examples: 8421
+  - name: train
+    num_bytes: 107345917
+    num_examples: 56355
   download_size: 26164664
   dataset_size: 154739992
 ---