serves a local directory (process.cwd() + 'public' is the default)
requests to /dir/ get answered by sending /dir/index.html back, if it exists.
npm i -g @grundstein/gms// show full help
gms --help
// serve the ./public directory
gms
// serve specific directory
gms --dir /global/directory/path
// serve on specific host and port
gms --host grundstein.it --port 2323