docs: Update docs to use yaml style when defining vars

[spetrosi]

Enhancement: Update docs to use yaml style when defining vars

Reason: The role was using an old jinja style definitions

[richm]

some background - constructs like varname: {key: value, ...} are JSON "embedded" in YAML. This is generally discouraged in Ansible - https://github.com/redhat-cop/automation-good-practices/tree/main/coding_style "Even if JSON is valid YAML and Ansible understands it, do only use JSON syntax if it makes sense (e.g. a variable file automatically generated) or adds to the readability. In doubt, nobody expects JSON so stick to YAML."

However, in some cases, it can make the code more readable e.g.

list_var: [a, b, c, d]

is imo more readable than

list_var:
  - a
  - b
  - c
  - d

for short lists with short list members