"Highly encourage" CORS

[benjaminoakes]

It would make sense to "highly encourage" JSON feed hosts to use the Access-Control-Allow-Origin: * header so that feed consumers can be JavaScript on a statically hosted site. This would enable easy mashups, etc.

(Aside: I think any GitHub Pages site now supports CORS out of the box, which makes Jekyll support an interesting use case.)

I propose that some wording about CORS is added to the spec. CORS shouldn't be required, but definitely recommended. Many of the feeds I've tried are not loadable without something like a CORS proxy, hence the creation of this issue.