Include geonode folder in doxyden search folders

Required to build the docs for this folder, and correctly
include the classes in the documentation coverage test

Author: nyalldawson

doc/CMakeLists.txt

@@ -61,6 +61,8 @@ IF(WITH_APIDOC)
       ${CMAKE_SOURCE_DIR}/src/core/effects
       ${CMAKE_SOURCE_DIR}/src/core/fieldformatter
       ${CMAKE_SOURCE_DIR}/src/core/geometry
+      ${CMAKE_SOURCE_DIR}/src/core/geocms
+      ${CMAKE_SOURCE_DIR}/src/core/geocms/geonode
       ${CMAKE_SOURCE_DIR}/src/core/gps
       ${CMAKE_SOURCE_DIR}/src/core/layertree
       ${CMAKE_SOURCE_DIR}/src/core/layout