Update README.md

The following have all forked ruby-processing, is anyone interested in maintaining ruby-processing at processing-1.5.1 (which is now frozen)?
@aviflombaum, @Epictetus, @jandot, @reaktivo, @roovo, @allant, @fjenett, @alx, @NevenaDjaja, @hbzhang, @gravitystorm, @visualisierte, @originalsurfmex, @sunnybythesea, @DekusDenial, @abachman, @joannecheng,@fo60213, @yush, @peterkrenn, @endymion, @fcoloni, @monkstone, @davidxv, @nicksieger, @macdiva, @designtestcode, @tegatai, @ahastudio, @michaelforrest, @jexchan, @maxhawkins, @dhaas, @tbueno, @ybakos, @prezjordan, @Rakasha, @andilar, @macournoyer, @benkant, @cjapes, @hassyx, @phren0logy, @maxehmookau, @imageoptimiser, @bassnode, @murasesyuka, @moumar, @jurisgalang, @naehrstoff, @sergheim, @tonytargonski, @utgarda, @ejjoo, @arubis, @mjording, @aaajiao, @mathpunk, @rubypoet, @daveyoon, @martinstannard, @jashkenas, @onehouse, @peterbenoit, @dhf2001, @BEATLES-OC, @weirdpercent