I am new to HA and trying to make sense from code snippets such as in this thread:
Is there a doc describing what can root nodes be in configuration.yaml and what is called what there (relationship between “integration”, “package”, “sensor”, “entity”)? It is kinda assumed it is all logical but the amount of documentation is overwhelming 
Immediate task is to have a card with all sensors battery level and the link above is exactly about that but I cannot translate those suggestions into actions - what integration or whatever should those definitions go under? Thanks!