Document default options for JSHint page

This documents the options that are enabled by default in JSHint. I pulled the
list of enabled options from `src/cli/default.json` in the JSHint project. The
formatting is not too great but the other option was to hack the `table2html`
function to accept three columns, which isn't that great either. Happy to switch
it around if need be.

I was a little confused about the `noempty` directive as the JSHint
documentation mentions that it's optional, yet it is enabled by default in
defaults.json.