Hello and thank you for using our service!
This is a good question. The short answer is technically yes it will work.
If you try the CDN url :
<your CDN prefix>.wpcdn.shift8cdn.com/readme.html
If the default WordPress readme.html file is there, it will load and be cached via the CDN.
Currently our WordPress plugin is not set to automatically rewrite any HTML static file url to go through the CDN simply because we didn’t think it would be something people wanted too much.
If you are talking about HTML rendered output on the site, this system can only cache static files that are routed or rewritten to go through the CDN. This means images, css, font files and those types of things will go through the CDN and hopefully speed up your site.
To just be a full on caching system we would need to route the ENTIRE site to go through the cdn, which would mean you would need to change your DNS to go through our systems. This simply isn’t possible at the moment.
If I misunderstood the question, please let me know.
Thanks!