推廣或降級 Swarm 節點

要提升節點或節點集，請從管理器節點執行 docker node promote：

docker node promote node-3 node-2

Node node-3 promoted to a manager in the swarm.
Node node-2 promoted to a manager in the swarm.

要降級節點或節點集，請從管理器節點執行 docker node demote：

docker node demote node-3 node-2

Manager node-3 demoted in the swarm.
Manager node-2 demoted in the swarm.