fix confusion w.r.t. which model to serialize and use in cpp_export tutorial

[Krovatkin]

Addressing feedback we got from @SethHWeidman .
Mainly, making sure there's no confusion which serialized model should be loaded in a c++ app.

[Krovatkin]

@brianjo would it be possible to merge a small update to this tutorial?

@SethHWeidman gave it a try and, unfortunately, it wasn't as clear as we would've hoped 😢

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[SethHWeidman]

Appreciate you making these changes @Krovatkin.

Could I request one more change? In the line near the end of the tutorial:

root@4b5a67132e81:/example-app/build# ./example-app model.pt

Could we change this to:

root@4b5a67132e81:/example-app/build# ./example-app traced_resnet_model.pt

Part of my confusion in going through this tutorial was that the example-app we have only works with the ResNet model since we are passing in a 4D Tensor, so if someone tries to run this with custom_model.pt, they'll get a confusing error.

Adding a note to this effect - that we are pushing a 4D Tensor through our model here, so this example-app will only work with a CNN model - would be even better 🙂

[Krovatkin]

Could we change this to:

Arrgh, I thought example.cpp was supposed to use MyModule. Fixed it.

[brianjo]

I'll merge this after it rebases. Thanks!

[SethHWeidman]

Hey @Krovatkin, don't mean to be a pest about this, but I meant the very last time we call example-app, where it prints a slice of the first five elements of the result of feeding the Tensor through the model. It still says

root@4b5a67132e81:/example-app/build# ./example-app model.pt

Could we change that line to:

root@4b5a67132e81:/example-app/build# ./example-app <path_to_model>/traced_resnet_model.pt

Or Brian or I can change directly on master after this merges. Thanks!

Update: made the change. @brianjo I'm not 100% familiar with our Pull Request system, but making a change to a file on an existing PR like this shouldn't be an issue, right?

[Krovatkin]

@SethHWeidman ah, you meant the output of a CMake script. Nice catch! Thanks for the update!