An alternative is to use an embedded diagramming syntax like dot or mermaid such that the diagrams are described as version controlled text and optionally rendered inline by e.g. VSCode. Cleaner than a litter of side car images in which it may be unclear what changed.
See Markdown Preview Enhanced: https://marketplace.visualstudio.com/items?itemName=shd101wy...
Or add Mermaid to the built-in markdown preview: https://marketplace.visualstudio.com/items?itemName=bierner....
You can also edit and enjoy these markdown pages with diagrams on Mac, iPad, iPhone: https://www.mweb.im/
Lastly, if anyone is not sure what to diagram for readers of architecture.md, consider the C4 model: