I have been using WebSequenceDiagrams [1] for years. Love it. It is declarative and simple, and works really well. The syntax seems similar but not the same as the OP article.

In a readme's or wiki page for an epic/story I often usually use a copy of the diagram image, with a link to edit the text/markup, or the text just in a collapsed wiki element. Though there are now also plugins for Confluence and more I believe.

[1] https://www.websequencediagrams.com/