Gateway: fallback routes per host, for the laptop's VPN address

README.md

@@ -37,6 +37,10 @@ Operators use the `wristcode` CLI inside the container, on junior.gib:
 t3 auth pairing create --scope orchestration:read --scope orchestration:operate --label "WristCode gateway"
 podman exec -it wristcode-gateway wristcode host add https://t3mac.gbrown.org <credential> --label "Mac mini"
 
+# A host reachable more than one way, such as a laptop with a VPN route, lists fallbacks.
+# The gateway tries them in order when the first does not answer.
+podman exec -it wristcode-gateway wristcode host add https://t3laptop.gbrown.org <credential> --label "Laptop" --alt-url https://t3laptopvpn.gbrown.org
+
 # Pair a watch: enter the printed code on the watch within 5 minutes.
 podman exec -it wristcode-gateway wristcode pair