Fix imsharpen docstring

[cpaniaguam]

https://github.com/WilhelmusLab/IceFloeTracker.jl/blob/3228e61d4a2f4878e48eda67ae1633a20923e2b5/src/normalization.jl#L64

[danielmwatkins]

Is this about fixing the function so that there are keyword arguments? Or which aspects are you aiming to fix?

[cpaniaguam]

@danielmwatkins That line shown above doesn't match the function's signature which changed to include the nondilated landmask as an argument. I just forgot to update it!