documentation of PercentElevRange

[vbuchauer]

Hello there,

when taking a closer look a the function PercentElevRange I discovered an error in the documentation of the function (https://www.whiteboxgeo.com/manual/wbt_book/available_tools/geomorphometric_analysis.html#percentelevrange).

The formula stated in the documentation is ${PER} = \frac{z_0}{(z_{min} - z_{max})} * 100 $
But in the code the following formula is used ${PER} = \frac{z_0 - z_{min}}{(z_{min} - z_{max})} * 100 $
As the function shall calculate a percentage, the actually used 2. formula makes more sense.

Maybe you could edit the documentation provided on the website.
Many Thanks!