title: How to use github flavored markdown in README.md file by default?
body: <p>The way markdown-style line end really annoys me, and I found gfm looks better.<br>
  But as I wrote the <code>.md</code> file and push it ti Github, it just shows as nomal markdown.<br>
  Judging the demo on github, it changes line without two blanks, isn't it?<br>
  This made me confusing. Just, how can I make this work?</p>