Implement Sphinx documentation

[Diego635]

We need to use sphinx for the documentation. This is the tool that creates the html help page and maybe a pdf documentation too.
The help html should look like a Wikipedia page. I think that is the format sphinx creates anyway.
There should be one page where the whole workflow is explained, with different chapters/sections and links to it from the content section at the beginning ("Wikipedia" format).
Then there could be a second page with known issues / errors and the way to solve them.
A way to give feedback should be there too. A link to GitHub, an e-mail...

[jaminzoda]

Sphinx documentation of code is implemented in 43101d9. However, the automatic documentation does not deal with the help on how to use the tool. It is instead the API documentation.