Create doxygen documentation of C++ API

:Release Notes:
Create doxygen documentation of C++ API

:Detailed Notes:
Create doxygen documentation of C++ API

:Testing Performed:
N/A

:QA Notes:
N/A

:Issues Addressed:
[BHV-1547] Create doxygen documentation of C++ API

Open-webOS-DCO-1.0-Signed-off-by: Sergiy Kryvonos <sergiy.kryvonos@lge.com>

Change-Id: Ief52ba911405d93aa60ff1fbc0be4505ec467bfc