add documentation

README.md

@@ -29,4 +29,4 @@ You are able specify output options:
   * `--short` (`-s`): removes borders
   * `--no-header`: removes headers
 * `--json` (`-j`): output is a json
-* `--wait` (`-w`) xx: wait xx seconds between each request
+* `--wait` (`-w`): specifiy the number of seconds between each request (defaut: 0)