Ubuntu 16.04 support ended April 2021.
Limited support is available to commercial customers via the Extended
Security Maintenance (ESM) program, but this is only for select
packages. So I think we are safe to drop this.
Use a "note" section for the Root on ZFS note.
Signed-off-by: szubersk <szuberskidamian@gmail.com>
Signed-off-by: Richard Laager <rlaager@wiktel.com>
[Split this out and rewrote commit message.]
