CNV-12191: Updating HCO version variable for 2.6.5

Author: ousleyp

modules/virt-document-attributes.adoc

@@ -14,7 +14,7 @@
 :ProductVersion:
 :VirtVersion: 2.6
 :KubeVirtVersion: v0.36.2
-:HCOVersion: 2.6.4
+:HCOVersion: 2.6.5
 // :LastHCOVersion:
 :product-build:
 :DownloadURL: registry.access.redhat.com