Debian/Ubuntu: Remove /boot/efi automount option

This was mentioned in #99 and I added it as an alternative option.
However, it seems to break GRUB; see #107.  GRUB tries to parse
/proc/mounts and see a line like this:
  systemd-1 /boot/efi autofs ...
From there, it gets "systemd-1" as the device name, and breaks.

Closes #107

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

docs/Getting Started/Ubuntu/Ubuntu 20.04 Root on ZFS.rst

@@ -768,21 +768,10 @@ Step 4: System Configuration
    For a mirror or raidz topology, repeat the `mkdosfs` for the additional
    disks, but do not repeat the other commands.
 
-   **Notes:**
-
-   - The ``-s 1`` for ``mkdosfs`` is only necessary for drives which present
-     4 KiB logical sectors (“4Kn” drives) to meet the minimum cluster size
-     (given the partition size of 512 MiB) for FAT32. It also works fine on
-     drives which present 512 B sectors.
-   - An alternate approach is to have ``/boot/efi`` automounted.  This
-     `reduces the risk of corruption of the ESP
-     <https://bugzilla.redhat.com/show_bug.cgi?id=1077984>`__.  To do so, add
-     it to ``/etc/fstab`` this way instead::
-
-       echo /dev/disk/by-uuid/$(blkid -s UUID -o value ${DISK}-part1) \
-           /boot/efi vfat \
-           x-systemd.idle-timeout=1min,x-systemd.automount,noauto \
-           0 1 >> /etc/fstab
+   **Note:** The ``-s 1`` for ``mkdosfs`` is only necessary for drives which
+   present 4 KiB logical sectors (“4Kn” drives) to meet the minimum cluster
+   size (given the partition size of 512 MiB) for FAT32. It also works fine on
+   drives which present 512 B sectors.
 
 #. Put ``/boot/grub`` on the EFI System Partition: