create section in docs recommending static IP addresses for etcd nodes in cluster

[vtrenton]

When setting up a Kubernetes cluster or really any etcd cluster - changing the underlying IP address of the node will cause connection issue between the nodes since what is in the database is a different address then what is actually running. On the Webpage I see NO mention of static IP requirements but I do see it called out in the recovery docs (https://etcd.io/docs/v3.5/op-guide/runtime-configuration/#restart-cluster-from-majority-failure) which makes me think it would be helpful to have this called out right away in the best practice documentation.

[mallardduck]

👍 Adding my self as a watcher.