add README.rdoc
add README.rdoc

ykzts/fastladder,onk/fastladder,fastladder/fastladder,id774/fastladder,toshimaru/fastladder,ykzts/fastladder,id774/fastladder,ykzts/fastladder,toshimaru/fastladder,fastladder/fastladder,onk/fastladder,fastladder/fastladder,onk/fastladder,id774/fastladder,toshimaru/fastladder