Fix typos in README for text-classification
Author: yoshitomo-matsubara
Pull request: yes

# What does this PR do?

`transformers/examples/pytorch/text-classification/run_glue_no_trainer.py` has `max_length` instead of `max_seq_length` while the README uses `--max_seq_length` as example commands for `run_glue_no_trainer.py`. This PR fixes the typos.
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## Before submitting
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