Set encryption=on

encryption=aes-256-gcm is now the default.

anarcat mentioned this in PR #306.

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

docs/Getting Started/openSUSE/openSUSE Tumbleweed Root on ZFS.rst

@@ -296,7 +296,7 @@ Step 2: Disk Formatting
        zpool create \
            -o cachefile=/etc/zfs/zpool.cache \
            -o ashift=12 \
-           -O encryption=aes-256-gcm \
+           -O encryption=on \
            -O keylocation=prompt -O keyformat=passphrase \
            -O acltype=posixacl -O canmount=off -O compression=lz4 \
            -O dnodesize=auto -O normalization=formD -O relatime=on \