adds README.md for pull request sample.

Hello 58snow,

I am asy524 and added README.md for trying *pull request*.
You can accept this pull request following instruction by github's.(or see [sample1](http://daicham.hatenablog.com/entry/20111005/1317829785) , or [sample2](http://akisute.com/2011/02/github-pull-request.html)).
If you done, send me a LINE message.

Thanks.