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

@@ -212,15 +212,15 @@ dataset_info:
   - name: idx
     dtype: int32
   splits:
-  - name: test
-    num_bytes: 18615474
-    num_examples: 87000
   - name: train
     num_bytes: 334809726
     num_examples: 1566000
   - name: validation
     num_bytes: 18607661
     num_examples: 87000
+  - name: test
+    num_bytes: 18615474
+    num_examples: 87000
   download_size: 146233621
   dataset_size: 372032861
 - config_name: discoverysmall
@@ -410,15 +410,15 @@ dataset_info:
   - name: idx
     dtype: int32
   splits:
-  - name: test
-    num_bytes: 187471
-    num_examples: 869
   - name: train
     num_bytes: 3355192
     num_examples: 15662
   - name: validation
     num_bytes: 185296
     num_examples: 871
+  - name: test
+    num_bytes: 187471
+    num_examples: 869
   download_size: 146233621
   dataset_size: 3727959
 ---