cppreference is the best you can do for C++. It isn't the documentation's fault that the language got so big and frequently introduces or deprecates features.

cppreference is best used for the normal workflow:

Search with Google, instantly find the correct page among the first 10 results, go there, skim the page, find what you need.

cppreference is more like man pages. You slowly build up your own mental map rather than having a structure enforced on you by hyperlinks and a directory hierarchy.

I find this model superior.