Link to github gist used to keep UML diagrams secure and versioned.
I hade drawing things with a mouse (remember we are typists first). Hense, I've introduced a text-to-diagram tool called mermaid to several companies. Also to protect the IP of a company, I avoid the use of online editors such as mermaidlive and draw.io so I keep all md files in source control.
The following github gist show what readMe will looks like.