OpenStack-Helm does not require release management

So far OpenStack-Helm has not used release management and is more
continuously released. While that may change in the future, let's
document that for now in governance.

Change-Id: I17878d95f8b005316661d83ec8030c8d626f5800

reference/projects.yaml

@@ -2466,18 +2466,23 @@ OpenStack-Helm:
   url: https://wiki.openstack.org/wiki/Openstack-helm
   deliverables:
     openstack-helm:
+      release-management: external
       repos:
         - openstack/openstack-helm
     openstack-helm-addons:
+      release-management: external
       repos:
         - openstack/openstack-helm-addons
     openstack-helm-docs:
+      release-management: external
       repos:
         - openstack/openstack-helm-docs
     openstack-helm-images:
+      release-management: external
       repos:
         - openstack/openstack-helm-images
     openstack-helm-infra:
+      release-management: external
       repos:
         - openstack/openstack-helm-infra