Add documentation support by version

[drkameleon]

Ideally, in our official site (https://arturo-lang.io) we should have:

• the current version documentation at: / (e.g. /documentation, etc) - this will correspond to the latest release
• the documention for each of the releases, from now on, e.g. /0.9.83/documentation)
• the master branch documentation, e.g. /master/documentation - pretty much like now, only it could be auto-generated via a Github action 😉