Fix doc example (#16448)

* Fix doc

* Make fixup
Co-authored-by: Niels Rogge <nielsrogge@nielss-mbp.home>

src/transformers/utils/doc.py

@@ -269,9 +269,10 @@ PT_SEQUENCE_CLASSIFICATION_SAMPLE = r"""
     ```python
     >>> # To train a model on `num_labels` classes, you can pass `num_labels=num_labels` to `.from_pretrained(...)`
     >>> num_labels = len(model.config.id2label)
-    >>> model = {model_class}.from_pretrained("{checkpoint}", num_labels=num_labels)
+    >>> model = {model_class}.from_pretrained(
+    ...     "{checkpoint}", num_labels=num_labels, problem_type="multi_label_classification"
+    ... )
 
-    >>> num_labels = len(model.config.id2label)
     >>> labels = torch.nn.functional.one_hot(torch.tensor([predicted_class_id]), num_classes=num_labels).to(
     ...     torch.float
     ... )