Fix typo in README.md (#61)

Fix typo in README.md

Author: chinglee-iot

README.md

@@ -94,7 +94,7 @@ By default, the submodules in this repository are configured with `update=none`
 
 To build unit tests, the submodule dependency of CMock is required. Use the following command to clone the submodule:
 ```
-git submodule update --checkout --init --recursive --test/unit-test/CMock
+git submodule update --checkout --init --recursive test/unit-test/CMock
 ```
 
 ### Platform Prerequisites