Adding lvgl.mk to my makefile

On the website it states: ‘LVGL can be easily integrated into any Makefile project by adding include lvgl/lvgl.mk to the main Makefile’. But where exactly can it be placed? I tried several places but I am getting the error that there is no rule to make target to build/lvgl. Does anyone have the fix?

reference: https://github.com/lvgl/lv_port_linux/blob/master/Makefile#L26

Thanks, I will try.