Correct naming pegasus x (#18896)

* add first generation tutorial

* [Pegasus X] correct naming

* [Generation] Remove

tests/models/pegasus_x/test_modeling_pegasus_x.py

@@ -559,7 +559,7 @@ class PegasusXModelIntegrationTests(unittest.TestCase):
         return PegasusTokenizer.from_pretrained("google/pegasus-x-base")
 
     def test_inference_no_head(self):
-        model = PegasusXModel.from_pretrained("pegasus-x-base").to(torch_device)
+        model = PegasusXModel.from_pretrained("google/pegasus-x-base").to(torch_device)
         input_ids = _long_tensor([[0, 31414, 232, 328, 740, 1140, 12695, 69, 46078, 1588, 2]])
         decoder_input_ids = _long_tensor([[2, 0, 31414, 232, 328, 740, 1140, 12695, 69, 46078, 1588]])
         inputs_dict = prepare_pegasus_x_inputs_dict(model.config, input_ids, decoder_input_ids)
@@ -574,7 +574,7 @@ class PegasusXModelIntegrationTests(unittest.TestCase):
         self.assertTrue(torch.allclose(output[:, :3, :3], expected_slice, atol=TOLERANCE))
 
     def test_inference_head(self):
-        model = PegasusXForConditionalGeneration.from_pretrained("pegasus-x-base").to(torch_device)
+        model = PegasusXForConditionalGeneration.from_pretrained("google/pegasus-x-base").to(torch_device)
 
         # change to intended input
         input_ids = _long_tensor([[0, 31414, 232, 328, 740, 1140, 12695, 69, 46078, 1588, 2]])