Publish docs on push

[Nycto]

This change adds a github workflow that auto-generates docs and publishes to a github page for every push to mainline. This is a pre-emptive pull request based on the conversation in #47. If if there is no interest in this, that's totally fine 👍

Getting this to work requires some administrative overhead to setup the correct branches and github tokens, as documented here: https://github.com/peaceiris/actions-gh-pages#github-pages-action

You can see an example of the generated outcome from another project, which uses a similar setup: https://necsusecs.github.io/Necsus/

[samdze]

This would be very useful!
Nim generated documentation HTMLs are not that great in my opinion but there sure is value in them for those that want to explore the API a bit