doc: update benchmark results

Author: panjf2000

README.md

@@ -92,7 +92,7 @@ Packet size     : 512/1024/2048/4096/8192/16384/32768/65536
 Test duration   : 15s
 ```
 
-#### Echo Server
+#### [Echo Benchmark](https://github.com/gnet-io/gnet-benchmarks)
 
 ![](https://github.com/panjf2000/gnet_benchmarks/raw/master/results/echo_conn_linux.png)
 

README_ZH.md

@@ -91,7 +91,7 @@ Packet size     : 512/1024/2048/4096/8192/16384/32768/65536
 Test duration   : 15s
 ```
 
-#### Echo Server
+#### [Echo 性能压测](https://github.com/gnet-io/gnet-benchmarks)
 
 ![](https://github.com/panjf2000/gnet_benchmarks/raw/master/results/echo_conn_linux.png)