Fix some error

vcaesar · vcaesar · commit c772f3e0be4d · 2017-07-01T00:15:54.000+08:00
diff --git a/zh/05.6.md b/zh/05.6.md
@@ -23,7 +23,7 @@ package main
 import (
 	"fmt"
 	"os"
-    "os/signal"
+	"os/signal"
 	"syscall"
 	"time"
 
