Run tests against the python code in our documentation

[mjvogelsong]

We can test the code block examples in our docs using pytest-markdown-docs! This should help us make sure our documentation examples are always runnable.

One open question is whether it is better to make most/every example a complete example? As a user of SDK docs, I kinda prefer that, because then every code block becomes fully-functional without any assumptions. We can highlight the "important" part of the code. But I do also think there's value in having shorter code snippets to focus on the important part. There is a python continuation fence that we can use to test against a series of python blocks.

TODOs:

• It already found some bugs -- e.g., we don't expose a confidence parameter in get_or_create_detector(). Gotta fix that.
• It would be nice to put asserts inline with the code blocks, but not render them...
• Switch all tests to hit prod instead of integ

[mjvogelsong]

Gotta fix this

[tyler-romero]

LGTM!