feat: Add support for multi versions in docs

[spotandjake]

This adds support for multiple versions in the docs, by default we serve the latest version to /docs/stdlib/list or what have you but you can also do /docs/v0.6.6/stdlib/list and switch between versions in the sidebar.

Questions:

• Do we want to include preview, we will need a workflow on the grain side to update it per commit to the main grain repo.

I split this into two commits to make it easier to review the first one is the code changes the second one is the documentation update.

Closes: #390