core: info message made dbg when adding a subst expression

src/core/ppcfg.c

@@ -80,7 +80,7 @@ int pp_subst_add(char *data)
 	}
 	pp_subst_rules_tail = pr;
 
-	LM_INFO("### added subst expression: %s\n", data);
+	LM_DBG("### added subst expression: [%s]\n", data);
 
 	return 0;
 }