2.2 implemented allowroot for server and proxy. this should be reflected in http://www.zabbix.com/documentation/2.2/manual/concepts/proxy

it currently says :

If you will try to run it as 'root', it will switch to a hardcoded 'zabbix' user, which must be present on your system.
These settings currently cannot be user configured, neither during compilation nor in the configuration file.

other pages should be reviewed (server description ?) to make sure they are uptodate