Update documentation of cnn_classification.py (#7486)

* Updated documentation of cnn_classification.py for much better understanding

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* Update computer_vision/cnn_classification.py

Co-authored-by: Caeden Perelli-Harris <caedenperelliharris@gmail.com>

Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>
Co-authored-by: Caeden Perelli-Harris <caedenperelliharris@gmail.com>