Run a specific test

doc/howto/dev/build_cn.md

@@ -53,6 +53,12 @@
    docker run -v $PWD:/paddle paddle:dev bash -c "cd /paddle/build; ctest"
    ```
 
+   有时候我们只想运行一个特定的单元测试，比如 `memory_test`，我们可以
+
+   ```bash
+   docker run -v $PWD:/paddle paddle:dev bash -c "cd /paddle/build; ctest -V -R memory_test"
+   ```
+
 ## 为什么要 Docker 呀？
 
 - 什么是 Docker?

doc/howto/dev/build_en.md

@@ -53,6 +53,12 @@ Nothing else.  Not even Python and GCC, because you can install all build tools
    docker run -v $PWD:/paddle paddle:dev bash -c "cd /paddle/build; ctest"
    ```
 
+   Sometimes we want to run a specific unit test, say `memory_test`, we can run
+
+   ```bash
+   docker run -v $PWD:/paddle paddle:dev bash -c "cd /paddle/build; ctest -V -R memory_test"
+   ```
+
 ## Docker, Or Not?
 
 - What is Docker?