Polish README, add time tunnel command showcase.

README.md

@@ -257,6 +257,27 @@ Affect(class-cnt:1 , method-cnt:1) cost in 109 ms.
  2018-09-20 09:45:42  org.apache.dubbo.demo.provider.DemoServiceImpl  sayHello  5      5        0     0.43        0.00%
 ```
 
+#### Time Tunnel(tt)
+
+Recording method invocation data, so that you can check the method invacation parameters, returned value and thrown exception later. It works as if you could come back and replay the past method invacation via time tunnel.
+
+```
+$ tt -t org.apache.dubbo.demo.provider.DemoServiceImpl sayHello
+Press Ctrl+C to abort.
+Affect(class-cnt:1 , method-cnt:1) cost in 75 ms.
+ INDEX   TIMESTAMP            COST(ms)  IS-RET  IS-EXP   OBJECT         CLASS                          METHOD
+-------------------------------------------------------------------------------------------------------------------------------------
+ 1000    2018-09-20 09:54:10  1.971195  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1001    2018-09-20 09:54:11  0.215685  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1002    2018-09-20 09:54:12  0.236303  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1003    2018-09-20 09:54:13  0.159598  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1004    2018-09-20 09:54:14  0.201982  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1005    2018-09-20 09:54:15  0.214205  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1006    2018-09-20 09:54:16  0.241863  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1007    2018-09-20 09:54:17  0.305747  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1008    2018-09-20 09:54:18  0.18468   true    false    0x55965cca     DemoServiceImpl                sayHello
+```
+
 #### Classloader
 
 ```

README_CN.md

@@ -249,6 +249,27 @@ Affect(class-cnt:1 , method-cnt:1) cost in 109 ms.
  2018-09-20 09:45:42  org.apache.dubbo.demo.provider.DemoServiceImpl  sayHello  5      5        0     0.43        0.00%
 ```
 
+#### Time Tunnel(tt)
+
+记录方法调用信息，支持事后查看方法调用的参数，返回值，抛出的异常等信息，仿佛穿越时空隧道回到调用现场一般。
+
+```
+$ tt -t org.apache.dubbo.demo.provider.DemoServiceImpl sayHello
+Press Ctrl+C to abort.
+Affect(class-cnt:1 , method-cnt:1) cost in 75 ms.
+ INDEX   TIMESTAMP            COST(ms)  IS-RET  IS-EXP   OBJECT         CLASS                          METHOD
+-------------------------------------------------------------------------------------------------------------------------------------
+ 1000    2018-09-20 09:54:10  1.971195  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1001    2018-09-20 09:54:11  0.215685  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1002    2018-09-20 09:54:12  0.236303  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1003    2018-09-20 09:54:13  0.159598  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1004    2018-09-20 09:54:14  0.201982  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1005    2018-09-20 09:54:15  0.214205  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1006    2018-09-20 09:54:16  0.241863  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1007    2018-09-20 09:54:17  0.305747  true    false    0x55965cca     DemoServiceImpl                sayHello
+ 1008    2018-09-20 09:54:18  0.18468   true    false    0x55965cca     DemoServiceImpl                sayHello
+```
+
 #### Classloader
 
 了解当前系统中有多少类加载器，以及每个加载器加载的类数量，帮助您判断是否有类加载器泄露。