create_or_find_kernel_and_ramdisk docstring fixes
create_or_find_kernel_and_ramdisk docstring fixes

Some modest docstring fixes will serve to alleviate developer confusion
(personally I have already been confused) as this function is no longer
accurately named.

Change-Id: If536f22755e24cdd67cbd83ac45fae69ed1c05b2
Partial-Bug: #1840709

openstack/tripleo-common,openstack/tripleo-common