Update getting started reference to reflect persistent node names

[eskibars]

In #19456 we dropped the "random fun Marvel characters" that were assigned to nodes, instead moving to persistent node names. https://github.com/elastic/elasticsearch/blob/master/docs/reference/getting-started.asciidoc#node needs to be touched up to reflect this.

A few of the examples in that doc are also superseded by the change and may be a little misleading, namely the auto-generated node name New Goblin that's referenced a few times on the page