docker: Recommend valkey

References: https://todo.xenrox.net/~xenrox/ntfy-alertmanager/24

docker/compose.yaml

@@ -8,10 +8,10 @@ services:
       - 127.0.0.1:8080:8080
     restart: unless-stopped
 
-  # Uncomment if you want to use redis as cache
-  # redis:
-  #   image: redis:alpine
-  #   container_name: redis
+  # Uncomment if you want to use valkey as cache
+  # valkey:
+  #   image: valkey/valkey
+  #   container_name: valkey
   #   restart: unless-stopped
   #   volumes:
   #     - ./cache:/data