Related #332.
Add doc-site target to make file and yml file to build the docs.
Following domenic's guide [1] but using leafo's gh actions like
luacheck.yml.
Builds the documentation for ldoc using the checked out version of ldoc
and uses peaceiris/actions-gh-pages to publish.
Once merged, docs will be available on https://lunarmodules.github.io/LDoc
[1]: https://gist.github.com/domenic/ec8b0fc8ab45f39403dd
David Briscoe
Pierre Chapuis
Caleb Maclennan