Virt, DPDK checkup: fix image build instruction

When running the `composer-cli compose image`, the image that is generated
is in the following template:
<UUID>-disk.qcow2
Currently the template is incomplete.

Signed-off-by: Bell Levin <[email protected]>

Author: bell-lev

modules/virt-building-vm-containerdisk-image.adoc

@@ -131,7 +131,7 @@ EOF
 +
 [source,terminal]
 ----
-$ virt-customize -a <UUID>.qcow2 --run=customize-vm --selinux-relabel
+$ virt-customize -a <UUID>-disk.qcow2 --run=customize-vm --selinux-relabel
 ----
 
 . To create a Dockerfile that contains all the commands to build the container disk image, enter the following command:
@@ -140,13 +140,13 @@ $ virt-customize -a <UUID>.qcow2 --run=customize-vm --selinux-relabel
 ----
 $ cat << EOF > Dockerfile
 FROM scratch
-COPY --chown=107:107 <uuid>-disk.qcow2 /disk/
+COPY --chown=107:107 <UUID>-disk.qcow2 /disk/
 EOF
 ----
 +
 where:
 
-<uuid>-disk.qcow2:: Specifies the name of the custom image in `qcow2` format.
+<UUID>-disk.qcow2:: Specifies the name of the custom image in `qcow2` format.
 
 . Build and tag the container by running the following command:
 +