The correct usage shall be `pip install -r requirements.txt` in README.md

[tcloaa]

Reference: https://stackoverflow.com/questions/42876592/unable-to-install-using-pip-install-requirements-txt/42876654

[tcloaa]

Also for those who encountered ModuleNotFoundError: No module named 'keras_text_summarization', see https://stackoverflow.com/questions/51157258/no-module-named-keras-text-summarization-when-running-keras-text-summarization

The documentation somehow needs to be modified, but overall this is a nice project, and very much thanks for the build!