Mod: update feature list

README.md

@@ -51,6 +51,7 @@ Finished List:
 - Codec
     * JsonRPC V2
     * Hessian V2
+    * [json for grpc](https://github.com/apache/dubbo-go/pull/582)
 
 - Protocol
     * Dubbo
@@ -111,6 +112,7 @@ Finished List:
     * [For jsonrpc](https://github.com/apache/dubbo-go/pull/335)
     * [For dubbo](https://github.com/apache/dubbo-go/pull/344)
     * [For grpc](https://github.com/apache/dubbo-go/pull/397)
+- 
 
 - Others:
     * start check

README_CN.md

@@ -50,6 +50,7 @@ Apache License, Version 2.0
 - 序列化协议
     * JsonRPC V2
     * Hessian V2
+    * [json for grpc](https://github.com/apache/dubbo-go/pull/582)
 
 - 协议
     * Dubbo