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

@@ -48,9 +48,6 @@ dataset_info:
   - name: selftext_urls
     sequence: string
   splits:
-  - name: test
-    num_bytes: 10419098
-    num_examples: 5411
   - name: train
     num_bytes: 166409797
     num_examples: 91772
@@ -60,6 +57,9 @@ dataset_info:
   - name: validation2
     num_bytes: 4737744
     num_examples: 2375
+  - name: test
+    num_bytes: 10419098
+    num_examples: 5411
   download_size: 72921829
   dataset_size: 194717224
 ---