rhel_kernel_workflow.adoc: Add missing images

@dzickusrh noticed that the two main KWF doc images were missing from the
original gdoc to adoc conversion.

Add the two images back to the doc.

Closes #38 (closed)

Suggested-by: Don Zickus dzickus@redhat.com
Signed-off-by: Prarit Bhargava prarit@redhat.com