Fixed suggestion in documentation resulting in linting error 'variables should be a map of key-valued strings'

Documentation now suggests a valid option with the intended result.

See #3147 (closed)

"yes", opposed to yes is not casted to a boolean. variables only accepts key-valued strings.

Better solution would be to change the parsing of variables (allow boolean or check the actual value of the string).

Status changed to merged

mentioned in commit 46e66f58