There are many tools that render some sort of schematic from RTL: simvision (schematic tracer), Joules, Genus...
Which one would be best for generating documentation style schematics from RTL, or at least a starting point that could then be edited in Visio or inkscape.
-> uses nice symbols for combinatorial logic (adders, multipliers), or better yet a simple cloud.
-> scriptable: rtl in -> desired hierarchy level -> svg / png out
-> essentially something like this, but not limited by Yosys verilog support (https://github.com/nturley/netlistsvg)
Yes, there is plenty of different document software. For example, until last year, I was using Microsoft software only. It sounds strange because a lot of people use quality software. Somehow I saw on youtube a video about a document software ClickHelp. When I saw for the first time the options of the ClickHelp, I was in a shock practically. It was much better than the Microsoft one. Now I'm using it, and I'd suggest checking https://clickhelp.com/ for more info. I hope that I could help someone.