How to create ph-pages for GitHub Pages on GitHub
Configuring a publishing source for GitHub Pages
git checkout --orphan gh-pages # create and checkout to an orphan branch
git reset . # reset
git clean -fxd # remove all files without .git, but I don't know why it works
echo 'Hello world' > index.html # 新增一個 hello word 的 html 檔
git commit -m 'init' # commit
git push -u origin gh-pages # push