Mermaid is fantastic for diagramming architecture. A little quirky, but not too bad. If you're using GitHub it's supported in any markdown file, and therefore

Mermaid is fantastic for diagramming architecture. A little quirky, but not too bad. If you're using GitHub it's supported in any markdown file, and therefore accessible to any other dev with repo access. No permissions issues, edits can go through code review, and no dependencies necessary.