Convention to support alt text in notebooks

I’ve tried using jupyter-book and quarto to produce html/book output from a series of notebooks and was wondering how to add alt text for output cells with figures. nbconvert [supports](https://github.com/jupyter/nbconvert/pull/1112) generating alt tags when alt is in the cell metadata. Should other apps adopt the same approach? Does there need to be more formal guidelines around this?

I was thinking of filing issues with jupyter-book/sphinx and quarto to ask that they support the same, but I don’t know if this one method should be adopted by all.

Link to discourse thread: https://discourse.jupyter.org/t/convention-to-support-alt-text/14936