Rename rel=prefetch to sapper:prefetch

[benmccann]

Sapper overrides the browser's default rel=prefetch behavior. There seemed to be agreement that we should stop doing this.

[arekbartnik]

I think it would also be good to change the rel=external. It feels weird to use existing attributes for different behaviors.

[Conduitry]

rel="external" is a real thing though, which already means precisely what Sapper is using as. https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/rel The problem with rel="prefetch" is that it looks like a real thing but it is not.

[arekbartnik]

@Conduitry what would you do if you had an sapper app on a [domain] with links to [domain]/[category] but [category] wasn’t part of your sapper app? Logically, all referenced resources are part of the site but not part of the sapper app. Using rel=external for these links is a “feel weird” part for me.