HOW to add Frr routing suite

hi edward here i want to know to add frr routing suite in feed and i am using make menuconfig gui method to make flash file to my route
i am also following method give in this link http://docs.frrouting.org/projects/dev-guide/en/latest/building-frr-for-openwrt.html#prepare-build-environment
i am using openwrt v18.06.05 stable release so is there any way to add to feed of v18.06.5 stable