When people join your team, stress this point. In the onboarding, require them to make at least one change to the documentation during their first week. People tend to think that documentation is someone else's responsibility, and it just isn't so.
The main problem is not a lack of documentation, but being able to find it. Search is woeful in all the documentation systems I've used. The only thing that can save the day is proper linking of related articles.
By default, people tend to throw documentation into a hierarchy. While that works for many things, it creates a structure that ultimately makes it hard to find things. Most documentation is related to a few different areas or domains, and with a hierarchy, you can only put it into a single "folder."
Any time you add a piece of documentation, you should link to it from at least two different places. Spend a moment and think about the person who will look for the thing you just documented. Where are they likely to look for it? Link it there.
If you ever look for something like OP, and can not find it easily, but ultimately do find it, add links to it in the places you looked earlier.
Over time, if enough people do this, the documentation will get decent or even good.
It's a solved problem in the sense that there is a solution, but the solution is not automatic. It requires someone to manage the process and the people to keep the documentation in a good state.
I wrote an article about this some time ago: https://koliber.com/articles/engineering-documentation-best-...