I really wish DX would go back to have a proper installable SDK with headers, libs, tools, integrated documentation and example code instead of those things being scattered across the Windows SDK and half the internet (and then half of the links becoming stale).

At least making the functional spec public was a massive step forward, this is much more useful than the actual API documentation, and also better than the documentation/specifications for most other 3D APIs:

https://microsoft.github.io/DirectX-Specs/