Add xlog in logging section

README.md

@@ -449,6 +449,7 @@ See [go-hardware](https://github.com/rakyll/go-hardware) for a comprehensive lis
 * [seelog](https://github.com/cihub/seelog) -   logging functionality with flexible dispatching, filtering, and formatting.
 * [stdlog](https://github.com/alexcesaro/log) - Stdlog is an object-oriented library providing leveled logging. It is very useful for cron jobs.
 * [tail](https://github.com/hpcloud/tail) - A Go package striving to emulate the features of the BSD tail program.
+* [xlog](https://github.com/rs/xlog) - A structured logger for `net/context` aware HTTP handlers with flexible dispatching.
 
 ## Machine Learning