message: update README about aead-cipher-extra
diff: @@ -37,6 +37,8 @@ shadowsocks is a fast tunnel proxy that helps you bypass firewalls.
  * `stream-cipher` - Enable deprecated stream ciphers. WARN: stream ciphers are UNSAFE!
  +* `aead-cipher-extra` - Enable non-standard AEAD ciphers
  +
  #### Memory Allocators
  This project uses system (libc) memory allocator (Rust's default). But it also allows you to use other famous allocators by features:
  