docs: Fixup format of a command line to build unit tests

docs/en/api-guides/unit-tests.rst

@@ -129,8 +129,8 @@ Change into tools/unit-test-app directory to configure and build it:
 * `idf.py menuconfig` - configure unit test app.
 
 * `idf.py -T all build` - build unit test app with tests for each component having tests in the ``test`` subdirectory.
-* `idf.py -T xxx build` - build unit test app with tests for specific components. 
-* `idf.py -T all -E xxxbuild` - build unit test app with all unit tests, except for unit tests of some components. (For instance: `idf.py -T all -E ulp mbedtls build` - build all unit tests exludes ulp and mbedtls components).
+* `idf.py -T "xxx yyy" build` - build unit test app with tests for some space-separated specific components (For instance: ``idf.py -T heap build`` - build unit tests only for ``heap`` component directory).
+* `idf.py -T all -E "xxx yyy" build` - build unit test app with all unit tests, except for unit tests of some components (For instance: ``idf.py -T all -E "ulp mbedtls" build`` - build all unit tests exludes ``ulp`` and ``mbedtls`` components).
 
 When the build finishes, it will print instructions for flashing the chip. You can simply run ``idf.py flash`` to flash all build output.
 

docs/zh_CN/api-guides/unit-tests.rst

@@ -155,11 +155,11 @@ DUT2（slave）终端：
 -  ``idf.py -T all build`` - 编译单元测试程序，测试每个组件 ``test``
    子目录下的用例。
 
--  ``idf.py -T xxx build`` - 编译单元测试程序，测试指定的组件。
+-  ``idf.py -T "xxx yyy" build`` - 编译单元测试程序，测试指定的组件。
 
--  ``idf.py -T all -E xxx build`` -
+-  ``idf.py -T all -E "xxx yyy" build`` -
    编译单元测试程序，测试所有（除开指定）的组件。例如
-   ``idf.py -T all -E ulp mbedtls build`` -
+   ``idf.py -T all -E "ulp mbedtls" build`` -
    编译所有的单元测试，不包括 ``ulp`` 和 ``mbedtls``\ 组件。
 
 当编译完成时，它会打印出烧写芯片的指令。您只需要运行 ``idf.py flash``