For managing services themselves I might recommend something like backstage.io but only from what I've heard, and not from personal experience.
Only you can know the operations of a service, so if a service had a /docs route (or a landing page or something) which documented what its purpose is, why it exists etc. and what needs to be running in order for it to achieve all that, then that might be a good first step. Beware of dated information though ...
