Yes, that's precisely what I meant by that paragraph. I have updated the documentation to hopefully be clearer, and to be more helpful by providing the entity names right there.
Custom Vending Setup -- Allows customizing monument vending machines. Works with vending machines spawned by this plugin that use the npcvendingmachine or shopkeeper_vm_invis prefabs.
Technically there are a bunch of other prefabs that start with npcvendingmachine_, which are all compatible, but if you are planning on customizing the vending machine, then it doesn't matter which prefab you use since you will be effectively overriding all the sale offers anyway.
Also, if you want to use an actual vendor NPC, you can spawn the vendor (bandit_shopkeeper) in the same place as an shopkeeper_vm_invis to achieve the same effect as vanilla shopkeepers.
You can also skin vending machines spawned by this plugin with maskin <skin id>.