bash completion for `docker daemon --cgroup-parent`

Signed-off-by: Harald Albers <github@albersweb.de>

contrib/completion/bash/docker

@@ -678,6 +678,7 @@ _docker_daemon() {
 		--authz-plugin
 		--bip
 		--bridge -b
+		--cgroup-parent
 		--cluster-advertise
 		--cluster-store
 		--cluster-store-opt