Fix typo in model name (#7268)

README.md

@@ -83,7 +83,7 @@ To download and use any of the pretrained models on your given task, you just ne
 >>> from transformers import AutoTokenizer, AutoModel
 
 >>> tokenizer = AutoTokenizer.from_pretrained("bert-base-uncased")
->>> model = AutoModel.from_pretrained("bert_base_uncased")
+>>> model = AutoModel.from_pretrained("bert-base-uncased")
 
 >>> inputs = tokenizer("Hello world!", return_tensors="pt")
 >>> outputs = model(**inputs)
@@ -93,7 +93,7 @@ or for TensorFlow:
 >>> from transformers import AutoTokenizer, TFAutoModel
 
 >>> tokenizer = AutoTokenizer.from_pretrained("bert-base-uncased")
->>> model = TFAutoModel.from_pretrained("bert_base_uncased")
+>>> model = TFAutoModel.from_pretrained("bert-base-uncased")
 
 >>> inputs = tokenizer("Hello world!", return_tensors="tf")
 >>> outputs = model(**inputs)