Clarify comments in configuration loader

The original comment used words like "higher" to mean "physically above
another element" and "lower" to mean "physically below another element" but
the list was numbered in increasing order, so item 3 was 'lower' than item 2
(isn't that confusing when 3 is lower than 2, but 3 is greater than 2
numerically). This is extremely counterintuitive for people who assume
"higher" means "numerically larger/greater", and "lower" means "numerically
smaller/less."

This changes the comment to be more specific and avoid descriptions that contrast physical list layout with numerical ordering.