Use machinery provided by PkgTemplates.jl

[Ratfink]

Generally, the easiest way to set up a new Julia package is to create the repository with PkgTemplates. This can automatically set up the necessary files for GitHub CI, building documentation on every commit, etc.

I realize it's a little late to get a clean start for this repository now without losing history, but we should be able to add the template-created files even at this slightly late stage. An easy way might be:

1. Use PkgTemplates to create an empty package with the same name
2. Copy the desired files into this repository, then add, commit, and push
3. Delete the empty package that PkgTemplates made