Add RHOSP to overview support list for HCP

Author: maxwelldb

modules/hosted-control-planes-overview.adoc

@@ -16,6 +16,7 @@
 * {aws-first}
 * {ibm-z-title}
 * {ibm-power-title}
+* {rh-openstack-first} 17.1, as a Technology Preview feature
 
 The {hcp} feature is enabled by default.