README.MD error about context settings

[azeller]

setting site_url (which will be the complete URI of the site root) doesn't need to be defined without the www, when adding the www-redirect in the system settings. Actually, it must not, and here's why:

Consider a site that has a FormIt Ajax-Call to a responder-template that responds JSON. This will have the site_url domain.com and be receiving a request from www.domain.com and therefore violate the CORS policy unless you explicitly allow cross-origin requests (which will be too high-level for most users).

Correct config would consequently be site_url WITH the www - so the final version of it and http_host WITHOUT it to make it redirectable.