OSDOCS-14588: Updates to Disconnected install

Author: EricPonvelle

_attributes/attributes-openshift-dedicated.adoc

@@ -54,4 +54,5 @@
 :hcp-title-first: {product-title} (ROSA) with {hcp} (HCP)
 :rosa-classic: ROSA (classic architecture)
 :rosa-classic-first: {product-title} (ROSA) (classic architecture)
+:egress-lockdown: {hcp-title} clusters with zero egress
 //ROSA CLI variables