INFRA-175 Configure https for docs.civicrm.org (and move to www-prod)
c.f. http://civicrm.stackexchange.com/questions/10699/where-to-report-gitbook-error-problem-loading-page
- currently docs.civicrm.org does not support https, which can cause problems because of the old "includeSubdomains" HSTS rule.
- docs should be on a CviCRM.org server.