As the comment by Yan mentions, closest you can get is Wiki, but its not meant for that, it requires auth to use it.
There is no such feature in Azure DevOps, I'm afraid.
This issue exists: https://visualstudio.uservoice.com/forums/330519-azure-devops-formerly-visual-studio-team-services/suggestions/16908766-support-for-static-doc-hosting-similar-compatible
