Provide a permanent version for the current spec for linking

Small thing, but while drafting some documentation for our implementation I wanted to link to the specific spec version we’ve currently implemented, which happens to be the current stable version (1.4.10).

However, the current version doesn’t yet have a permanent version in the “versions” page (https://www.rosetta-api.org/versions.html) like older versions, such as (for example) 1.4.0 ( https://www.rosetta-api.org/docs/1.4.0/welcome.html).

Ideally, the current version should also be offered in the list of older versions or a redirect from the future permalink (https://.../docs/1.4.10) to the current version (https://.../docs/current) should be added so that docs can point to the exact reference specs they comply with.