Inconsistent output of code example in Proprocessing Chapter in Docu
The following [docu](https://huggingface.co/docs/transformers/preprocessing) contains some inconsistent/wrong output examples for the `Build Tensor` subsection:

```python
batch_sentences = [
    "But what about second breakfast?",
    "Don't think he knows about second breakfast, Pip.",
    "What about elevensies?",
]
encoded_input = tokenizer(batch, padding=True, truncation=True, return_tensors="pt")
print(encoded_input)
```
Output:
```txt
{'input_ids': tensor([[  101,   153,  7719, 21490,  1122,  1114,  9582,  1623,   102],
                      [  101,  5226,  1122,  9649,  1199,  2610,  1236,   102,     0]]), 
 'token_type_ids': tensor([[0, 0, 0, 0, 0, 0, 0, 0, 0],
                           [0, 0, 0, 0, 0, 0, 0, 0, 0]]), 
 'attention_mask': tensor([[1, 1, 1, 1, 1, 1, 1, 1, 1],
                           [1, 1, 1, 1, 1, 1, 1, 1, 0]])}
```

The output does not contain the applied truncation and padding and also misses the last sentence of `batch_sentences`. This also applies to the TensorFlow example. 
