README.md in ougai-1.5.6 vs README.md in ougai-1.5.7

- old
+ new
@@ -349,9 +349,10 @@
 - [Customize Sidekiq logger](https://github.com/tilfin/ougai/wiki/Customize-Sidekiq-logger)
 - [Forward logs to Fluentd](https://github.com/tilfin/ougai/wiki/Forward-logs-to-Fluentd)
 - [Forward logs to Logentries](https://github.com/tilfin/ougai/wiki/Forward-logs-to-Logentries)
 - [Use as ServerEngine logger](https://github.com/tilfin/ougai/wiki/Use-as-ServerEngine-logger)
 - [Forward logs to Loggly](https://github.com/tilfin/ougai/wiki/Forward-logs-to-Loggly)
+- [Use as Rack logger](https://github.com/tilfin/ougai/wiki/Use-as-Rack-logger)
 
 ## License
 
 [MIT](LICENSE.txt)