add intro for #293 in readme

README.md

@@ -89,6 +89,8 @@ We provide a vscode extension - [Goc Coverage](https://marketplace.visualstudio.
     2. After service restarted and test finished, collect coverage again with `goc profile -o b.cov`
     3. Merge two coverage profiles together: `goc merge a.cov b.cov -o merge.cov`
 
+5. By default, goc will use the artifact's file name as its service name. You can overwrite it by setting environment variable `GOC_SERVICE_NAME`. (See [#293](https://github.com/qiniu/goc/issues/293) for details)
+
 ## RoadMap
 - [x] Support code coverage collection for system testing.
 - [x] Support code coverage counters clear for the services under test at runtime.

README_zh.md

@@ -87,6 +87,8 @@ goc 可以实时收集长时运行的 golang 服务覆盖率。收集步骤只
     2. 测试结束后，通过 `goc profile -o b.cov` 命令再收集一次覆盖率
     3. 通过 `goc merge a.cov b.cov -o merge.cov` 命令合并两次的覆盖率
 
+5. 默认情况下，goc使用编译产物的名称作为注册标识。你可以通过设置 `GOC_SERVICE_NAME` 环境变量以自定义该标识（可参见 [#293](https://github.com/qiniu/goc/issues/293)）。 
+
 ## Blogs
 
 - [Go语言系统测试覆盖率收集利器 goc](https://mp.weixin.qq.com/s/DzXEXwepaouSuD2dPVloOg)