Update readme.md

readme.md

@@ -43,12 +43,13 @@ RapidJSON is a header-only C++ library. Just copy the `include/rapidjson` folder
 
 To build the tests and examples:
 
-1. Obtain [premake4](http://industriousone.com/premake/download).
-2. Copy premake4 executable to `rapidjson/build` (or system path).
-3. Change directory to `rapidjson/build/`, run `premake.bat` on Windows, `premake.sh` on Linux or other platforms.
-4. On Windows, build the solution at `rapidjson/build/vs2008/` or `/vs2010/`.
-5. On other platforms, run GNU `make` at `rapidjson/build/gmake/` (e.g., `make -f test.make config=release32`; `make -f example.make config=debug32`).
-6. On success, the executables are generated at `rapidjson/bin`.
+1. Execute `git submodule update --init` to get the files of thirdparty submodules (google test).
+2. Obtain [premake4](http://industriousone.com/premake/download).
+3. Copy premake4 executable to `rapidjson/build` (or system path).
+4. Change directory to `rapidjson/build/`, run `premake.bat` on Windows, `premake.sh` on Linux or other platforms.
+5. On Windows, build the solution at `rapidjson/build/vs2008/` or `/vs2010/`.
+6. On other platforms, run GNU `make` at `rapidjson/build/gmake/` (e.g., `make -f test.make config=release32`; `make -f example.make config=debug32`).
+7. On success, the executables are generated at `rapidjson/bin`.
 
 To build the [Doxygen](http://doxygen.org) documentation: