[DOCS] clarify pillar datastructure of underlying yaml

[whytewolf]

Description
Some users are having difficulty when setting up pillar in referencing those different pillar structures after words.

Suggested Fix
describe in detail how the different layouts in pillar data affect the change in the underlying data structure when being reference in jinja as well as describe how the json data relates.

Type of documentation
Salt documentation and getting started guide.

Location or format of documentation
https://docs.saltproject.io/en/latest/topics/tutorials/pillar.html