upd tutorial in md

README.md

@@ -9,10 +9,15 @@ license: mit
 ```
 from datasets import load_dataset
 
-data = load_dataset("george-chou/Pima", split="train")
+trainset = load_dataset("george-chou/Pima", split="train[:80%]")
+testset = load_dataset("george-chou/Pima", split="train[-20%:]")
 
-for item in data:
+for item in trainset:
     print(item)
+
+for item in testset:
+    print(item)
+
 ```
 
 ## Maintenance