Document consuming the Python implementation

### 🤔 What's the problem you've observed?

Require appropriate documentation for consuming the Python implementation appropriately to make it easy to adopt and ensure is used in the most effective manner.

### ✨ Do you have a proposal for making it better?

Once the package has been published, to define an optimal implementation while replacing respective code within the [Cucumber Messages Python package tests](https://github.com/cucumber/messages/blob/51fb5275a6cc8ddabffa2db9952b53c4288a7ed7/python/tests/test_model_load.py) and update the respective documentation in the compatibility kit accordingly.

### 📚 Any additional context?

_No response_

Start with python/tests/test_model_load.py in the linked Cucumber Messages Python package and review how the implementation is currently consumed. Then locate the compatibility kit documentation and determine the changes needed after the package is published. Done means the Python consumption guidance is documented and the relevant test code and compatibility-kit documentation reflect the recommended implementation.

Written by the indexing model from the issue text.