INFRA-211 Setup redirect from book.civicrm.org to docs.civicrm.org
Currently http://book.civicrm.org/anything redirects to https://civicrm.org/documentation. It would be better for documentation links to go to the right place.
So http://book.civicrm.org/user/* should redirect to https://docs.civicrm.org/user/en/stable/*
Original author: colemanw