Add README to https://pypi.org/project/minesweeper/

[MartinThoma]

Currently, the page on PyPI is empty: https://pypi.org/project/minesweeper/

With the suggested change, it could look like this:

• https://pypi.org/project/propy3/
• https://github.com/MartinThoma/propy3/blob/master/setup.cfg

As you can see in the propy3 example, you could move all metadata to setup.cfg. This would make the setup.py slimmer. setuptools.setup will pick it up automatically.

[MartinThoma]

For this to take effect, you need to upload a new version to PyPI