Fix myst reference errors

[mwcraig]

See this for what is likely the fix: https://myst-parser.readthedocs.io/en/latest/syntax/optional.html#auto-generated-header-anchors

Edit: Two ways forward here:

• Add jupyterlab-myst as a runtime dependency (e.g. in binder, environment, pip requirements, etc)
• Write a custom function to slugify the anchors.

[mwcraig]

This turns out to be sort of a mess. See: https://github.com/orgs/executablebooks/discussions/1036

I think the magical myst setting can be put in the sphinx section of the configuration rather than doing a source code hack.