Created by: wangkuiyi

In this PR https://github.com/PaddlePaddle/book/pull/137 from @qingqing01 , I noticed that the recognize_digits/README.md files in our develop branch has ^M at the end of most lines.

This PR removes these ^M's using

sed 's/^M//g' README.md > new
mv new README.md

where ^M was typed as Ctrl-V and Ctrl-M.