Explore any SEO benefit from better url slugs for demo notebooks

[drbenvincent]

At the moment we get URL's like this https://causalpy.readthedocs.io/en/stable/notebooks/its_pymc.html

If we have more descriptive notebook names than its_pymc then there is potential for SEO.

• Explore if this would make a difference
• Come up with new naming scheme - update AGENTS.md to embody that naming policy.
• Update them all
• This will break historical links in social media posts etc. So explore if there's a way to do some fancy stuff to not break old links