HACK CRIO: set docker.io as a source for unqualified images

roles/container_runtime/templates/crio.conf.j2

@@ -152,7 +152,7 @@ image_volumes = "mkdir"
 
 # registries is used to specify a comma separated list of registries to be used
 # when pulling an unqualified image (e.g. fedora:rawhide).
-# registries = []
+registries = ['docker.io']
 
 # The "crio.network" table contains settings pertaining to the
 # management of CNI plugins.