Ensure auto-generated entries such as --help are present for completion by calling Validate()

tools/cli/completion-main.go

@@ -88,6 +88,7 @@ func GenerateCompletions(args []string) error {
 		re(root)
 	}
 
+	root.Validate()
 	all_completions := make([]*Completions, 0, 1)
 	for _, argv := range all_argv {
 		all_completions = append(all_completions, root.GetCompletions(argv, init_completions[output_type]))