Create a documentation site

[robertcorponoi]

We need better documentation than just the readme.

I've come across a few options like mdBook, VuePress, etc but I think I've decided on creating a Gridsome site and host it on Netlify or GitHub pages.

This means that changing documentation will require working in a different repo but it's a better alternative than having an npm library within the cargo package. We could also set up an action to copy the build files of the documentation into a /docs directory in this repo and use it with GitHub pages.