text: Title: [TrOCR] Failed to execute the example of Evaluation of IAM
  Body: Thank you for your wonderful work on TrOCR.
  
  I am trying to repeat the example of "[Evaluation of IAM](https://github.com/microsoft/unilm/tree/master/trocr#evaluation-on-iam)". Model I am using is TrOCR base: trocr-base-handwritten.pt
  
  The problem arises when using the command line:
  
  $(which fairseq-generate) \
          --data-type STR --user-dir ./ --task text_recognition --input-size 384 \
          --beam 10 --scoring cer2 --gen-subset test --batch-size ${BSZ} \
          --path ${MODEL} --results-path ${RESULT_PATH} --preprocess DA2 \
          --bpe gpt2 --dict-path-or-url https://layoutlm.blob.core.windows.net/trocr/dictionaries/gpt2_with_mask.dict.txt \ # --bpe sentencepiece --sentencepiece-model ./unilm3-cased.model --dict-path-or-url https://layoutlm.blob.core.windows.net/trocr/dictionaries/unilm3.dict.txt ## For small models
          --fp16 \
          ${DATA}
  
  The bug is: **syntax error near unexpected token `--data-type'** as the image attached:
  ![image](https://user-images.githubusercontent.com/32938376/207506292-a6083c71-72a0-48c1-bd7b-ce50c6ff92b9.png)
  
  I searched the fairseq command line information page ([link](https://fairseq.readthedocs.io/en/latest/command_line_tools.html)), I could not find the option for "--data-type".
  
  Can you please let me know how you set up the IAM evaluation and which version of "fairseq" are you using.
  
  Thank you in advance
  
  - Platform: ubuntu20.04 with cuda:11.3.1
  - Python version: python 3.7
  - PyTorch version (GPU?): 1.11 with GPU
  