[docs] Creating issue tracker on github

[INADA Naoki]

Hi,

Currently, we use Python's issue tracker for documentation bugs.
https://docs.python.org/3/bugs.html#documentation-bugs

But roundup is not easy to use for new people recent days.
I think Github's issue tracker is more friendly for users.

How about creating repository for document bug report?
Maybe, https://github.com/python/docs-issues or
https://github.com/python-docs/issues

Regards,