Update README.md

README.md

@@ -34,6 +34,14 @@ print(next(iter(ds)))
 ```
 
 ## Data Structure
+```
+DatasetDict({
+    train: Dataset({
+        features: ['src', 'complexity', 'problem', 'from'],
+        num_rows: 4517
+    })
+})
+```
 
 ### Data Instances