More informative message at ONNX export (#609)
* better message
* yet better message
* format
* Update optimum/exporters/onnx/convert.py
Co-authored-by: Michael Benayoun <mickbenayoun@gmail.com>
* Update optimum/exporters/onnx/__main__.py
Co-authored-by: Michael Benayoun <mickbenayoun@gmail.com>
* renaming
Co-authored-by: Michael Benayoun <mickbenayoun@gmail.com>
