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

@@ -35,12 +35,12 @@ dataset_info:
   - name: dialog
     list: string
   splits:
-  - name: test
-    num_bytes: 1498216
-    num_examples: 10000
   - name: train
     num_bytes: 932634902
     num_examples: 6820506
+  - name: test
+    num_bytes: 1498216
+    num_examples: 10000
   - name: validation
     num_bytes: 2922731
     num_examples: 20000