Update Thrift Doc

docs/cn/thrift.md

@@ -29,6 +29,7 @@ sudo make install
 ```bash
 sh config_brpc.sh --headers=/usr/include --libs=/usr/lib --with-thrift
 ```
+注意: 在编译用户代码的时候, 请定义ENABLE_THRIFT_FRAMED_PROTOCOL宏, 否则在include brpc中thrift协议相关头文件后, 实际并不生效
 
 # Client端访问thrift server
 基本步骤：

docs/en/thrift.md

@@ -29,6 +29,7 @@ Config brpc with thrift support, then make. The compiled libbrpc.a includes exte
 ```bash
 sh config_brpc.sh --headers=/usr/include --libs=/usr/lib --with-thrift
 ```
+PS: Please Define ENABLE_THRIFT_FRAMED_PROTOCOL Marco in user code in order to make it work when including thrift utils headers in brpc.
 
 # Client accesses thrift server
 Steps：