Add guidance on Publish to NPM docs for more than just "integrations"

[sarah11918]

We don't really have a great way of making some of the newer resources like design systems/components discoverable because they are not technically integrations. But, if they use one of our special keywords in their package.json, (e.g. astro-component) then their npm package will show up in the integrations catalogue.

We could make sure that a wider audience knows that this is possible, and after we have decided on and documented the process, specifically contact:

https://accessible-astro-starter.incluud.dev/accessible-components/,
https://ui.full.dev/
https://ui.studiocms.dev/
https://starwind.dev/
https://www.shadcnblocks.com/
https://astrobits.dev/

[louisescher]

I feel like a category specifically for component libraries makes sense, as the current CSS + UI category also covers UI frameworks like @astrojs/react and @astrojs/vue. Seeing as it's already a combined category, and lots of CSS optimization integrations live there, a new category makes sense for the libraries like Starwind and StudioCMS UI that introduce a whole design system instead of just a singular component.