Modified Doxygen to be build by default, but I may remove this. For development, it's kind of annoying.

CMakeLists.txt

@@ -187,13 +187,15 @@ add_dependencies(Hello YAML-CPP)
 
 
 # add a target to generate API documentation with Doxygen
+# ALL make documentation build by default if possible
 find_package(Doxygen)
 	if(DOXYGEN_FOUND)
 	configure_file(${CMAKE_CURRENT_SOURCE_DIR}/Documentation/Doxyfile.in ${CMAKE_CURRENT_BINARY_DIR}/Documentation/Doxyfile @ONLY)
 	add_custom_target(doc
-	${DOXYGEN_EXECUTABLE} ${CMAKE_CURRENT_BINARY_DIR}/Documentation/Doxyfile
-	WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
-	COMMENT "Generating API documentation with Doxygen" VERBATIM
+		ALL
+		${DOXYGEN_EXECUTABLE} ${CMAKE_CURRENT_BINARY_DIR}/Documentation/Doxyfile
+		WORKING_DIRECTORY ${CMAKE_CURRENT_BINARY_DIR}
+		COMMENT "Generating API documentation with Doxygen" VERBATIM
 	)
 	endif(DOXYGEN_FOUND)