Update to include example of LM

The model files have been updated in order to include the classification layers, based on https://github.com/huggingface/transformers/issues/2901, and now can be also used as a LM.

model_cards/nlpaueb/bert-base-greek-uncased-v1/README.md

@@ -68,6 +68,47 @@ tokenizer = AutoTokenizer.from_pretrained("nlpaueb/bert-base-greek-uncased-v1")
 model = AutoModel.from_pretrained("nlpaueb/bert-base-greek-uncased-v1")
 ```
 
+## Use Pretrained Model as a Language Model
+
+```python
+import torch
+from transformers import *
+
+# Load model and tokenizer
+tokenizer_greek = AutoTokenizer.from_pretrained('nlpaueb/bert-base-greek-uncased-v1')
+lm_model_greek = AutoModelWithLMHead.from_pretrained('nlpaueb/bert-base-greek-uncased-v1')
+
+# ================ EXAMPLE 1 ================
+text_1 = 'O ποιητής έγραψε ένα [MASK] .'
+# EN: 'The poet wrote a [MASK].'
+input_ids = tokenizer_greek.encode(text_1)
+print(tokenizer_greek.convert_ids_to_tokens(input_ids))
+# ['[CLS]', 'o', 'ποιητης', 'εγραψε', 'ενα', '[MASK]', '.', '[SEP]']
+outputs = lm_model_greek(torch.tensor([input_ids]))[0]
+print(tokenizer_greek.convert_ids_to_tokens(outputs[0, 5].max(0)[1].item()))
+# the most plausible prediction for [MASK] is "song"
+
+# ================ EXAMPLE 2 ================
+text_2 = 'Είναι ένας [MASK] άνθρωπος.'
+# EN: 'He is a [MASK] person.'
+input_ids = tokenizer_greek.encode(text_1)
+print(tokenizer_greek.convert_ids_to_tokens(input_ids))
+# ['[CLS]', 'ειναι', 'ενας', '[MASK]', 'ανθρωπος', '.', '[SEP]']
+outputs = lm_model_greek(torch.tensor([input_ids]))[0]
+print(tokenizer_greek.convert_ids_to_tokens(outputs[0, 3].max(0)[1].item()))
+# the most plausible prediction for [MASK] is "good"
+
+# ================ EXAMPLE 3 ================
+text_3 = 'Είναι ένας [MASK] άνθρωπος και κάνει συχνά [MASK].'
+# EN: 'He is a [MASK] person he does frequently [MASK].'
+input_ids = tokenizer_greek.encode(text_3)
+print(tokenizer_greek.convert_ids_to_tokens(input_ids))
+# ['[CLS]', 'ειναι', 'ενας', '[MASK]', 'ανθρωπος', 'και', 'κανει', 'συχνα', '[MASK]', '.', '[SEP]']
+outputs = lm_model_greek(torch.tensor([input_ids]))[0]
+print(tokenizer_greek.convert_ids_to_tokens(outputs[0, 8].max(0)[1].item()))
+# the most plausible prediction for the second [MASK] is "trips"
+```
+
 ## Evaluation on downstream tasks
 
 TBA