[dovecot/core] 0ad3de: man: Update doveadm director flush description

[GitHub]

  Branch: refs/heads/master
  Home:   https://github.com/dovecot/core
  Commit: 0ad3dea8cb36fc8211b42c1aef9ed42c95fd3747
      https://github.com/dovecot/core/commit/0ad3dea8cb36fc8211b42c1aef9ed42c95fd3747
  Author: Timo Sirainen <timo.sirainen at dovecot.fi>
  Date:   2016-11-30 (Wed, 30 Nov 2016)

  Changed paths:
    M doc/man/doveadm-director.1.in

  Log Message:
  -----------
  man: Update doveadm director flush description