fix(slideshare): use `url` for join path

Before : http://www.slideshare.net/teppeis/latest-closurecompiler/ -> http://www.slideshare.net/teppeis/latest-closurecompiler//6
After   : http://www.slideshare.net/teppeis/latest-closurecompiler/ ->  http://www.slideshare.net/teppeis/latest-closurecompiler/6
chore(readme): release to readme