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

@@ -32,15 +32,15 @@ dataset_info:
           0: negative
           1: positive
   splits:
-  - name: test
-    num_bytes: 216868
-    num_examples: 1821
   - name: train
     num_bytes: 4690022
     num_examples: 67349
   - name: validation
     num_bytes: 106361
     num_examples: 872
+  - name: test
+    num_bytes: 216868
+    num_examples: 1821
   download_size: 7439277
   dataset_size: 5013251
 ---