This also adds a [.editorconfig](https://editorconfig.org/) and adds
apidoc.md to the gitignore.

Windows is infinitely cursed.

Greatly appreciated.

* Made finddesc.lua execute commands using `sh -c 'command'`, which ensures that Unix-like shell is used instead of cmd.exe
* Made finddesc.lua avoid a situation where it would end up with a double '/' in `outpath`
* Redirect output of deleting the document to null to avoid pointless "No such file or directory" errors.

Doesn't seem to break anything, though I wish Microsoft would fix their filesystems.

Markdown changes are a nice touch, though they'll be replaced soon.

Might think about using #!/usr/bin/env for Lua at some point.

* It didn't add spaces after the ## or #, which made them not work as headings in some renderers, so I fixed this.
* I then made it add newlines to make it look nicer without being rendered.

1. Made the Lua thing used be an optional variable, so it works for different Lua versions and locations

2. Made it work better with windows filesystems being weird with trailing dots.