Transfer Learning Example lacks the depth required to showcase Flux about model-zoo

[logankilpatrick]

Ideally, this would include at least some commentary on the way the data is being setup, some way of knowing the model trained (adding validation to training) or checking accuracy at the end with the test set, etc.

[mcabbott]

Comments above refer to the version on fluxml.github.io, which FluxML/fluxml.github.io#156 has deleted. Moving the issue to the model zoo.