Add refactored CMake example

app/CMakeLists.txt

@@ -0,0 +1,8 @@
+set(MY_EXE "app")
+
+add_executable(${MY_EXE} "src/main.cpp")
+
+target_link_libraries(${MY_EXE} "moduleA" "moduleB" "moduleC")
+
+# no need to include directories, because they are included automatically
+# thanks to exposing the directories using PUBLIC