Add the README file to the Python package (#1665)
Add the README file to the Python package (#1665)

* package: include README for PyPI page

PyPI supports Markdown for the long_description for packages now, we
should include the README.md so that the project page looks a bit nicer.

See https://pypi.org/project/streamlink/0.12.1/#description

* package: improve the list of classifiers

* setup: added some more links and the supported python versions

As suggested by @back-to

melmorabity/streamlink,bastimeyer/streamlink,chhe/streamlink,gravyboat/streamlink,melmorabity/streamlink,javiercantero/streamlink,wlerin/streamlink,beardypig/streamlink,back-to/streamlink,back-to/streamlink,javiercantero/streamlink,bastimeyer/streamlink,wlerin/streamlink,gravyboat/streamlink,chhe/streamlink,streamlink/streamlink,streamlink/streamlink,beardypig/streamlink