INSTALL: Added description how to create additional dove* user/group.
`doveauth' user and group for the authentication process and the group
`dovemail' for mail related Dovecot processes.
# All parameters are described in pgsql_table(5) / PGSQL PARAMETERS
#
# The hosts that Postfix will try to connect to and query from.
hosts = localhost
# The user name and password to log into the pgsql server.
user = postfix
password = some_password
# The database name on the servers.
dbname = mailsys
# The SQL query template used to search the database
query = SELECT gid FROM postfix_gid WHERE domainname='%d'