Correct os-refresh-config README.md typo and format
Correct os-refresh-config README.md typo and format

Replace `run-parts' with `dib-run-parts' since os-refresh-config is
using it. Correct markdown code block format.

Change-Id: If0184b80d0f35bc30f9799135bd4f659889bcbbd

rdo-management/tripleo-image-elements,radez/tripleo-image-elements,radez/tripleo-image-elements,openstack/tripleo-image-elements,openstack/tripleo-image-elements,rdo-management/tripleo-image-elements