When multiple versions of the documentation are available, it tends to pollute google results. As a way to prevent that, it would be good to always have the latest stable release available under /current/, and have all previous versions + the master docs contain canonical links to the current docs like:

<link rel="canonical" href="http://.../current/..." />

That way it consolidates all results under the current URL which will always be correct, and it also encourages people linking to docs in blog posts and such to use links that will not rot.

/cc @alexcrichton