Add Navigate Through Poses tutorial and improve BT behavior-tree documentation#879

FelixZF-Happy wants to merge 1 commit intoros-navigation:masterros-navigation/docs.nav2.org:masterfrom

FelixZF-Happy:zf/master/nav_through_posesFelixZF-Happy/docs.nav2.org:zf/master/nav_through_posesCopy head branch name to clipboard