Add documentation section for --override option
Add documentation section for --override option

This patch is a followup of [1], adding a documentation
section of the '--override' option.

[1] https://softwarefactory-project.io/r/#/c/17372/

Change-Id: Iad65fd7ca0c91157f5b5f22fc3da6ffd913ea0d8

openstack-packages/rdopkg,openstack-packages/rdopkg,redhat-openstack/rdopkg,redhat-openstack/rdopkg