png_set_quantize final argument is not documented in libpng-manual.txt

[benkasminbullock]

This is in pngrtrans.c:

/* Dither file to 8-bit.  Supply a palette, the current number
 * of elements in the palette, the maximum number of elements
 * allowed, and a histogram if possible.  If the current number
 * of colors is greater than the maximum number, the palette will be
 * modified to fit in the maximum number.  "full_quantize" indicates
 * whether we need a quantizing cube set up for RGB images, or if we
 * simply are reducing the number of colors in a paletted image.

It would be nice to mention it in libpng-manual.txt too.