Fix and improve references and link them to readme

[Xuzzo]

Currently references are quite hidden in the docs folder. Also they do not seem to be a comprehensive list. Fix that.

[mdbenito]

Obviously, remember to have all references in Zotero and use an export here. Do NOT add a manually generated text file.

Besides the rather obvious benefits of centralization and collaborative curation, we have then the possibility of easily adding the references to the website, or using them to plan a block seminar, without having to dig for files at random locations in different projects.

[Xuzzo]

I have done a quick patch of this in #33. Will need to figure out how to do it through Zotero export.