Yeah, I've lived this. Built one at my last gig. The portal became this beautiful graveyard while everyone just Slacked each other or dug through old repos.
The thing that actually worked: stop optimizing for discoverability first. Just make it trivial to update. We switched to a single markdown file per service, auto-generated from actual config, living in the repo. Ugly as hell. But when someone fixed something, the docs fixed themselves. Adoption went up because it wasn't stale by Thursday.
Golden paths are fine. But don't make them the bottleneck for the 20% of legit edge cases.