Improve documentation about configuring Python models

[lokitoth]

VW is configured, in most use cases, through a command-line-like syntax. This enables easy transition between using it in tool form to library form, but is more complex in Python.

The Python bindings translate inputs to constructors of the model classes (pyvw.vw, VWClassifier, VWRegressor, VWMultiClassifier, etc.) into the command-line options, but there is no clear documentation or tutorial about how the mapping works, leading to confusing, as in #3065

Tasks

• [ ] Create tutorial diving into the various configuration options when used in Python
• [ ] Ensure that Python documentation explains how command-line arguments map into Python

[Sandy4321]

great idea