Correct/clarify `?growth_rate` regarding `h`

[brookslogan]

        • "rel_change": uses (B/A - 1) / h, where B is the average of
          'y' over the second half of a sliding window of bandwidth h
          centered at the reference point 'x0', and A the average over
          the first half. This can be seen as using a first-difference
          approximation to the derivative.

"/ h" and "second half of a sliding window of bandwidth h" seem incompatible. It appears that "/ h" is true if x are evenly spaced with no gaps (maybe with some compatibility assumptions about different arithmetic operations on x vs on indices of x). And it seems like "second half of a sliding window of bandwidth h" should involve "2h".