setup-spoke.sh: print exact authorized_keys command with public key when displaying hub key instructions

spoke/setup-spoke.sh

@@ -215,6 +215,10 @@ case "$KEY_CHOICE" in
     cat "$KEY_PATH.pub"
     echo -e "${YELLOW}══════════════════════════════════════════${NC}"
     echo ""
+    echo -e "${YELLOW}  On the hub, run as ${HUB_USER}:${NC}"
+    echo ""
+    echo "  echo "$(cat "$KEY_PATH.pub")" >> /home/${HUB_USER}/.ssh/authorized_keys"
+    echo ""
     read -rp "Press ENTER once the key has been added to ${HUB_HOST}..."
     ;;
 2)