Review documentation links

With the improved documentation site some of the links to documentation pages are broken and should be reviewed (ex: there is a `user` link pointing to http://doc.nuxeo.com/display/NXDOC/REST+API+Entity+Types#user which is supposed to provide the JSON payload to create a user, but the link is dead the link should be https://doc.nuxeo.com/nxdoc/rest-api-entity-types/#user)