Is it somehow possible to insert yuml (https://yuml.me/diagram/scruffy/class/samples) diagrams into vsts-wiki pages?
I've tried it using the image markdown syntax:

Or a more complex one:

But the wiki page doesn't render it, instead the markdown is shown in plain text.
Yes, yuml diagrams are supported for VSTS wiki page.
Just use the default yuml syntax , such as: