Ubuntu 22.04 / Debian: Deprecate zsys

Ubuntu almost removed support for ZFS from the installer, and zsys is
on life support:
https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1966773
https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1968150

I plan to rework the Ubuntu 22.04 instructions to be closer to those for
Debian Buster.  This will be straightforward, but I need to actually test
the resulting instructions before pushing that change.

Signed-off-by: Richard Laager <rlaager@wiktel.com>

docs/Getting Started/Ubuntu/Ubuntu 22.04 Root on ZFS.rst

@@ -12,46 +12,12 @@ Overview
 Ubuntu Installer
 ~~~~~~~~~~~~~~~~
 
-The Ubuntu installer has `support for root-on-ZFS
-<https://arstechnica.com/gadgets/2020/03/ubuntu-20-04s-zsys-adds-zfs-snapshots-to-package-management/>`__.
-This HOWTO produces nearly identical results as the Ubuntu installer because of
-`bidirectional collaboration
-<https://ubuntu.com/blog/enhancing-our-zfs-support-on-ubuntu-19-10-an-introduction>`__.
-
-If you want a single-disk, unencrypted, desktop install, use the installer. It
-is far easier and faster than doing everything by hand.
-
-If you want a ZFS native encrypted, desktop install, you can `trivially edit
-the installer
-<https://linsomniac.gitlab.io/post/2020-04-09-ubuntu-2004-encrypted-zfs/>`__.
-The ``-o recordsize=1M`` there is unrelated to encryption; omit that unless
-you understand it. Make sure to use a password that is at least 8 characters
-or this hack will crash the installer. Additionally, once the system is
-installed, you should switch to encrypted swap::
-
-  swapon -v
-  # Note the device, including the partition.
-
-  ls -l /dev/disk/by-id/
-  # Find the by-id name of the disk.
-
-  sudo swapoff -a
-  sudo vi /etc/fstab
-  # Remove the swap entry.
-
-  sudo apt install --yes cryptsetup
-
-  # Replace DISK-partN as appropriate from above:
-  echo swap /dev/disk/by-id/DISK-partN /dev/urandom \
-      swap,cipher=aes-xts-plain64:sha256,size=512 | sudo tee -a /etc/crypttab
-  echo /dev/mapper/swap none swap defaults 0 0 | sudo tee -a /etc/fstab
-
-`Hopefully the installer will gain encryption support in
-the future
-<https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1857398>`__.
-
-If you want to setup a mirror or raidz topology, use LUKS encryption, and/or
-install a server (no desktop GUI), use this HOWTO.
+The Ubuntu installer still has ZFS support, but `it was almost removed for
+22.04 <https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1966773>`__
+and `it no longer installs zsys
+<https://bugs.launchpad.net/ubuntu/+source/ubiquity/+bug/1968150>`__.  At
+the moment, this HOWTO still uses zsys, but that will be probably be removed
+in the near future.
 
 Raspberry Pi
 ~~~~~~~~~~~~