minor update to readme
minor update to readme

mikelum/pyspeckit,allisony/pyspeckit,bsipocz/pyspeckit,pyspeckit/pyspeckit,bsipocz/pyspeckit,dinossimpson/pyspeckit,pyspeckit/pyspeckit,e-koch/pyspeckit,keflavich/pyspeckit-obsolete,allisony/pyspeckit,keflavich/pyspeckit,jpinedaf/pyspeckit,mikelum/pyspeckit,jpinedaf/pyspeckit,keflavich/pyspeckit,low-sky/pyspeckit,low-sky/pyspeckit,e-koch/pyspeckit,vlas-sokolov/pyspeckit,vlas-sokolov/pyspeckit,dinossimpson/pyspeckit