[Feature]: Documentation on running graphs created in Rivet using Python

### Feature Request

Super neat project, thanks for open-sourcing! In the Show HN Hacker News post [here](https://news.ycombinator.com/item?id=37433218), it says:

> Finally, Rivet is built to be embedded into a larger application (TypeScript for now, but we've also found a way to run it in Python).

I couldn't find any documentation on how to run a Rivet graph via Python (though I did find the example project for executing Python code via Rivet https://github.com/abrenneke/rivet-plugin-example-python-exec). Would it be possible to share how you're running these graphs with Python instead of TypeScript?

Also, I expect it may not be likely, but are there any plans for first-class Python support in the future?

### Code of Conduct

- [X] I agree to follow this project's Code of Conduct

Start by reviewing the Rivet project’s existing embedding documentation and the linked rivet-plugin-example-python-exec project to identify how Python currently interacts with Rivet graphs. Document the supported way to run a graph from Python, including prerequisites and an example, and clarify whether first-class Python support is planned.

Written by the indexing model from the issue text.