Fix docs on PyPI
**Describe the bug**
The PyPI package page has broken links and images.

**To Reproduce**

Go to https://pypi.org/project/pyxel/ - see images are missing.
Click on English and see README.md gives a not found error.

I don't know if this ever worked or how much work it would be fix, but it would give a more polished image and first impression of the package especially for newcomers who find it on PyPI before GitHub.

**Screenshots**
![Screen Shot 2021-03-05 at 1 33 17 pm](https://user-images.githubusercontent.com/18750745/110110455-8479e400-7db7-11eb-98bc-81f372be7e82.png)

