readme: Please treat TILDE as a BertLMHeadModel model:
  ```
  from transformers import BertLMHeadModel, BertTokenizerFast
  
  model = BertLMHeadModel.from_pretrained("ielab/TILDE")
  tokenizer = BertTokenizerFast.from_pretrained('bert-base-uncased')
  ```
  
  Github: https://github.com/ielab/TILDE