d-i manual: 3 "jessie" remain in current guide

[victory <victory.deb@gmail.com>]

these should be updated as this is for stretch :)

post-install/post-install.xml:32-
  Under the SysV init system <command>halt</command> had the same
  effect as <command>poweroff</command>, but with systemd as init
  system (the default in jessie) their effects are different.

the default since jessie
or
the default in stretch

no idea if these are still valid also for stretch;

boot-installer/arm.xml:55-
      The graphical installer is not enabled on the arm64 &d-i; images
      for jessie so the serial console is used. 

boot-installer/arm.xml:108-
      ... Also USB is not supported in the jessie kernel so
      installing from a USB stick does not work. ...

-- 
victory
no need to CC me :-)