User feedback on supersampled PSFs

[josePhoenix]

@AndreaBellini would like us to improve the documentation on obtaining supersampled PSFs. Here's the current section: http://pythonhosted.org/webbpsf/webbpsf.html#pixel-scales-sampling-and-oversampling

I understand that Andrea wanted a PSF sampled at a different pixel scale than the detector pixels, and was frustrated by the fact that options['parity'] = 'odd' determines the parity of the final down-sampled array and not the OVERSAMP extension. The answer ended up being to change the pixelscale attribute and supply an odd number of pixels to fov_pixels=.

Could you suggest how we should improve this section, @AndreaBellini?