welcome: mention oVirt on OKD

using attribute to show oVirt instead of RHV when
generating OKD documentation.

Signed-off-by: Sandro Bonazzola <[email protected]>

Author: sandrobonazzola

welcome/index.adoc

@@ -59,7 +59,7 @@ To troubleshoot OpenStack installation issues, you can
 xref:../installing/installing_openstack/installing-openstack-troubleshooting.adoc#installing-openstack-troubleshooting[view instance logs and ssh to an instance].
 ////
 
-- **Install a cluster on Red Hat Virtualization**: You can deploy clusters on Red Hat Virtualization with a
+- **Install a cluster on {rh-virtualization-first}**: You can deploy clusters on {rh-virtualization-first} with a
 xref:../installing/installing_rhv/installing-rhv-default.adoc#installing-rhv-default[quick install] or an
 xref:../installing/installing_rhv/installing-rhv-customizations.adoc#installing-rhv-customizations[install with customizations].