add config for a small sample

README.md

@@ -35,6 +35,8 @@ configs:
         path: "stage2/valid_stage2.parquet"
       - split: test
         path: "stage2/test_stage2.parquet"
----
-
-# Test readme!
+  - config_name: sample
+    data_files:
+      - split: validation
+        path: "stage2/valid_stage2.parquet"
+---