README.hardware: update beaglebone entry to match KERNEL_IMAGETYPE

U-boot 2014.07 defaults to using a gzip compressed kernel
image (zImage). A proper change upading KERNEL_IMAGETYPE has already
been introduced to beaglebone machine config. This patch updates manual
steps to creating a SD card image with proper kernel image name.

(From meta-yocto rev: f1b4b97415e3bb16b1b9119e8339e0bf454c7335)

Signed-off-by: Maciej Borzecki <maciej.borzecki@open-rnd.pl>
Signed-off-by: Maciek Borzecki <maciek.borzecki@gmail.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

README.hardware

@@ -251,14 +251,14 @@ if used via a usb card reader):
   5. If using core-image-minimal rootfs, install the modules
      # tar x -C /media/root -f modules-beaglebone.tgz
 
-  6. If using core-image-minimal rootfs, install the kernel uImage into /boot
+  6. If using core-image-minimal rootfs, install the kernel zImage into /boot
      directory of rootfs
-     # cp uImage-beaglebone.bin /media/root/boot/uImage
+     # cp zImage-beaglebone.bin /media/root/boot/zImage
 
   7. If using core-image-minimal rootfs, also install device tree (DTB) files
      into /boot directory of rootfs
-     # cp uImage-am335x-bone.dtb /media/root/boot/am335x-bone.dtb
-     # cp uImage-am335x-boneblack.dtb /media/root/boot/am335x-boneblack.dtb
+     # cp zImage-am335x-bone.dtb /media/root/boot/am335x-bone.dtb
+     # cp zImage-am335x-boneblack.dtb /media/root/boot/am335x-boneblack.dtb
 
   8. Unmount the SD partitions, insert the SD card into the Beaglebone, and
      boot the Beaglebone