Remove output directive

[fwkoch]

Previously, when ingesting jupyter notebooks for myst, we created an in-memory markdown "file." For cell outputs, the output data was moved to a cache, keyed off arbitrary id, then we used an output directive in the markdown "file" with that id to inject the output back into the document... Now we just go straight from notebook to mdast; much more straight-forward and understandable, I think.

However, the little output directive with only an id is still lingering in our myst-directives (and the docs!). This directive does not have any user-facing functionality and now has no internal functionality either. I think we should just remove it.

[stevejpurves]

@fwkoch is there anything downstream that might be using this? a unist select() one of the themes for example?

https://github.com/executablebooks/myst-theme/blob/ec6cd2b8bf0cb53292e99bf3d2bcb212236fc876/packages/jupyter/src/execute/provider.tsx#L90

or do you mean to remove the directive but maintain the node type?

[agoose77]

@stevejpurves your example is the output AST node which we do use, it's just the directive that's redundant.