general clarification, less theLuggage importance

Not sure if you're down with it, but hoping to lessen the importance of theLuggage, as it isn't an absolute requirement, and it's hard for beginners.
Otherwise bumped OS testing matrix, clarified path to script, added wording around processing stuff(since nothing is explicitly ‘defined’ besides placement), added wording for testing/ad hoc addition of items requiring specific perms/ownership along with one-liner, updated link to munki project code