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

@@ -58,12 +58,12 @@ dataset_info:
   - name: source
     dtype: string
   splits:
-  - name: test
-    num_bytes: 458218
-    num_examples: 2110
   - name: train
     num_bytes: 1829167
     num_examples: 8437
+  - name: test
+    num_bytes: 458218
+    num_examples: 2110
   download_size: 750717
   dataset_size: 2287385
 ---