Create doc page

[ktong]

So user can access doc at http://wangkuiyi.github.io/pysqlflow/

[tonyyang-svail]

@ktong follow https://github.com/wangkuiyi/pysqlflow/pull/36#pullrequestreview-207721107, pushed branch _gh: https://github.com/wangkuiyi/pysqlflow/tree/_gh

[ktong]

could make link (http://wangkuiyi.github.io/pysqlflow/) works for document?

[zhangdavids]

👋 👍