Open
Description
Problem
Right now the user documentation of mdbook is hosted on the github.io domain: https://rust-lang.github.io/mdBook/ I think it would be better to move it to be a subdomain of rust-lang.org, e.g. https://mdbook.rust-lang.org
Proposed Solution
In order to accomplish this one needs to configure the DNS and in the repository of the project set the subdomain (and click on enforce https).
The previous site will automatically redirect to the new one.
What do you think?