[draazon]

There's a place for UML in the README.md; as some other commenters have pointed out, UML works much better as a sketching tool than as a total definition of a software system. A couple of quick class diagrams at the top level (probably generated using something like https://plantuml.com/) might provide a better communication model than text.

[manbash]

Yes plantuml is still my go-to visual design tool, whenever I feel information is missing, and I actually prefer it over mermaid (which has been integrated in github markdown), which I found very lacking.

What I like about text-based tools like plantuml/mermaid is the ability to see diffs in PR.

Other industry modeling tool use binary databases to represent the UML model and make it harder (i.e. need to use their specific diff visualizers, if available) to review changes of the design.

Maybe plantuml should be adopted and maintained. Unfortunately it is still stuck in a Java implementation...

[bbkane]

It does have a very good VS Code plugin providing autocomplete and (somewhat laggy) diagram preview