Set up a sitemap for google indexing of npmx

[lino-levan]

Right now, npmx doesn't rank very highly, if at all, ideally it'd show up pretty high on any npm package google search.

[lino-levan]

Maybe @danielroe disagrees about ranking on arbitrary npm packages?

From discord:

this shouldn't be possible as we disallowed anything except home page

[danielroe]

I'm disallowing it only until we go public.

[vinnymac]

In the meantime how do we want to approach the sitemap? Is the intention to configure https://nuxt.com/modules/sitemap here when we are ready for one?