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

@@ -51,12 +51,12 @@ dataset_info:
   - name: cited_doc_ids
     sequence: int32
   splits:
-  - name: test
-    num_bytes: 33625
-    num_examples: 300
   - name: train
     num_bytes: 168627
     num_examples: 1261
+  - name: test
+    num_bytes: 33625
+    num_examples: 300
   - name: validation
     num_bytes: 60360
     num_examples: 450