the documentation is built and installed

debian/xtpcpp-doc.install

-debian/tmp/usr/share/doc/xtpcpp/xtpcpp-doc.pdf usr/share/doc/xtpcpp
-debian/tmp/usr/share/doc/xtpcpp/html usr/share/doc/xtpcpp
+usr/share/doc/xtpcpp
+usr/share/doc/xtpcpp
 

doc/user-manual/CMakeLists.txt

@@ -45,11 +45,11 @@ if(BUILD_USER_MANUAL)
 
   install(FILES
     ${CMAKE_CURRENT_SOURCE_DIR}/build/user-manual/user-manual_color_en.pdf
-    DESTINATION ${DOC_DIR}/${TARGET}-doc.pdf)
+    DESTINATION share/doc/xtpcpp/${TARGET}-doc.pdf)
 
   install(DIRECTORY 
     ${CMAKE_CURRENT_SOURCE_DIR}/build/user-manual/html/user-manual/
-    DESTINATION ${DOC_DIR}/html)
+    DESTINATION share/doc/xtpcpp/html)
 
   message("")
   message(STATUS "${BoldGreen}Finished configuring the ${CMAKE_PROJECT_NAME} user manual.${ColourReset}")