Use mkdocs and add gitpod configuration

[osfanbuff63]

Resolves #22.

Adds mkdocs using the material theme, and mkdocstrings
to auto-generate references from the code.

This also adds an actions workflow to deploy the docs to Pages whenever a commit to main is pushed. You may need to enable Pages and set it to deploy using GitHub Actions, but this might be done automatically with actions/configure-pages.

In addition, I've added a gitpod configuration.

I've made this a PR as it's quite big, so just to not throw anyone else off this is a different branch.

[nsde]

I don't know about the last change with the main.py. Maybe we should except both? Is the exception type OS-dependent?

Apart from that, LGTM.

[osfanbuff63]

I don't know about the last change with the main.py. Maybe we should except both? Is the exception type OS-dependent?

Apart from that, LGTM.

The OSError class is the base for both WinError and probably something similar for Unix-based systems. The FileNotFoundError should be derived from OSError so we should be fine, but that's a change for another day I guess.

[osfanbuff63]

@nsde should we just merge this or do you have anything else to say?

[nsde]

@nsde should we just merge this or do you have anything else to say?

I dunno