update webpack.md
update webpack.md

szyablitsky/react_on_rails,shakacode/react_on_rails,shakacode/react_on_rails,shakacode/react_on_rails,szyablitsky/react_on_rails,shakacode/react_on_rails,shakacode/react_on_rails,szyablitsky/react_on_rails,szyablitsky/react_on_rails