Improve Gen python bindings documentation: generated files are not ac…

…tually created (#639)

* doc: Modify an generated files in document that is not actually created

Helloworld.py is not generated by FastDDSGen, by cmake and make.

Signed-off-by: Seong Jin Kim <mirusu400@naver.com>

* Update docs/fastdds/getting_started/simple_python_app/includes/dataType.rst

Co-authored-by: Jesús Poderoso <120394830+JesusPoderoso@users.noreply.github.com>
Signed-off-by: Seong Jin Kim <mirusu400@naver.com>

* Update docs/fastdds/getting_started/simple_python_app/includes/dataType.rst

Co-authored-by: Jesús Poderoso <120394830+JesusPoderoso@users.noreply.github.com>
Signed-off-by: Seong Jin Kim <mirusu400@naver.com>

---------

Signed-off-by: Seong Jin Kim <mirusu400@naver.com>
Co-authored-by: Jesús Poderoso <120394830+JesusPoderoso@users.noreply.github.com>

docs/fastdds/getting_started/simple_python_app/includes/dataType.rst

@@ -52,6 +52,16 @@ This must have generated the following files:
     * HelloWorldCdrAux.hpp: C++ header file for HelloWorldCdrAux.ipp.
     * CMakeLists.txt: CMake file to generate C++ source code and Python module from the `SWIG`_ interface files,
       compile and generate C++ libraries.
+
+After that, the python bindings can be generated by running the following command.
+
+.. code-block:: bash
+
+    cmake .
+    make
+
+This must have generated the python binding:
+
     * HelloWorld.py: Python module to be imported by your Python example.
 
 CMakeLists.txt