Simpler example introduction

[Aylr]

The examples show too many options. There should be a run this first.py that is a simple 10 liner that loads a pre-built dataset, and trains a single model (pick one).

Then lead users to the more advanced examples that show pulling data from different places, other algorithms, etc.

This needs to be blended into the docs in a nice clean way.

Bonus points if this aligns with the R package. https://github.com/HealthCatalyst/healthcareai-r/issues/647