message: Add ssmanager in Notes
diff: @@ -324,6 +324,7 @@ It supports the following features:
  * [x] [SIP002](https://github.com/shadowsocks/shadowsocks-org/issues/27) Extension ss URLs
  * [x] HTTP Proxy Supports ([RFC 7230](http://tools.ietf.org/html/rfc7230) and [CONNECT](https://tools.ietf.org/html/draft-luotonen-web-proxy-tunneling-01))
  * [x] Defend against replay attacks, [shadowsocks/shadowsocks-org#44](https://github.com/shadowsocks/shadowsocks-org/issues/44)
  +* [x] Manager APIs, supporting [Manage Multiple Users](https://github.com/shadowsocks/shadowsocks/wiki/Manage-Multiple-Users)
  ## TODO
  