Variable color demo page (website)

[Tait <gnu...@t4...>]

Someone just asked, "how do I map a 4th dimension to line
color?" I was surprised to discover that the varcolor demo,
which answers exactly this question, is nowhere to be found on
http://gnuplot.sourceforge.net/demo_4.6/.

How does one go about updating/creating a patch for the demo pages?