Step-by-step guide or process to get an existing model into Vertex using this tool

[archena]

Is your feature request related to a problem? Please describe.
The reference example does not show how to bring your own model code/training pipelines. We want an easy and documented way to add and modify model training code.

Describe the solution you'd like

• Document adding and/or modifying model training code in this reference example
• Add/modify convenience functions and wrappers of vertex:edge to suit this task

Additional context
The issue is related to #3, that will allow multiple models in the repo, so the solution for this issue should ideally account for that.