[nfc] fix typo examples/community/roberta

[digger-yu]

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📝 What does this PR do?

fix typo examples/community/roberta
detail info

    modified:   examples/community/roberta/README.md
    modified:   examples/community/roberta/preprocessing/README.md
    modified:   examples/community/roberta/pretraining/README.md
    modified:   examples/community/roberta/pretraining/arguments.py
    modified:   examples/community/roberta/pretraining/model/bert.py
    modified:   examples/community/roberta/pretraining/run_pretraining.py
    modified:   examples/community/roberta/pretraining/utils/exp_util.py
    modified:   examples/community/roberta/pretraining/utils/global_vars.py

please check
ColossalAI\examples\community\roberta\pretraining\model\bert.py
line 330 bhrd to bhld is right

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