Improve post image creation instructions

src/freedombone-image

@@ -380,7 +380,8 @@ if [[ $IMAGE_TYPE != "virtualbox"* && $IMAGE_TYPE != "qemu"* ]]; then
     echo ''
     echo $'You can copy the image to a microSD card with:'
     echo ''
-    echo "    sudo dd bs=1M if=$(ls ${PROJECT_NAME}*.img) of=/dev/sdX conv=fdatasync"
+    echo "    unxz ${PROJECT_NAME}*.img.xz"
+    echo "    sudo dd bs=1M if=${PROJECT_NAME}*.img of=/dev/sdX conv=fdatasync"
     echo ''
 fi