Feature Request: Add support for versioned docs

[paolosimone]

It would be nice to tie the docs version with the compiler release.

At the time of writing the latest compiler release is v0.41.0, but the online docs already refer to changes that have been merged in master but not released yet, such as Traits.

It took me a while to understand why the compiler was complaining, since I assumed that the examples in the doc would work with the latest available release.

Probably it's not super-priority in this stage of the project since the API is expected to change rapidly, but in the (near?) future consider adding a dropdown menu in the docs to select a target compiler version.

[magnus-madsen]

Ah yes- We should do this at some point.

A new compiler release is imminent, until then you have to write "class".