doc BUGFIX trees information organization

Remove duplicated groups of schema information and improve overall
organization and coverage for schema and data groups in doxygen.
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 217257b..875edc9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -333,6 +333,7 @@
     add_custom_target(doc
             COMMAND ${DOXYGEN_EXECUTABLE} ${CMAKE_BINARY_DIR}/Doxyfile
             WORKING_DIRECTORY ${CMAKE_CURRENT_SOURCE_DIR})
+    string(REPLACE ";" " " DOXY_HEADERS "${headers}")
     configure_file(Doxyfile.in Doxyfile)
 endif()