readme: This model is a non-finetuned RAG-Token model and was created as follows:
  ```python
  from transformers import RagTokenizer, RagSequenceForGeneration, AutoTokenizer
  
  model = RagSequenceForGeneration.from_pretrained_question_encoder_generator(
      "facebook/dpr-question_encoder-single-nq-base",
      "facebook/bart-base"
  )
  
  question_encoder_tokenizer = AutoTokenizer.from_pretrained("facebook/dpr-question_encoder-single-nq-base")
  generator_tokenizer = AutoTokenizer.from_pretrained("facebook/bart-base")
  
  tokenizer = RagTokenizer(question_encoder_tokenizer, generator_tokenizer)
  model.config.use_dummy_dataset = True
  model.config.index_name = "exact"
  
  model.save_pretrained("./")
  tokenizer.save_pretrained("./")
  ```
  