connection to the Guide

[egpbos]

One of the decisions that I apparently missed during the holidays was to sever all links to the Guide. The README contained a reference to it in the first paragraph and the PR template also contained a checkbox to make sure that the Python chapter in the Guide was in line with this template, as was the general plan for the template for years.

Do we indeed want to get rid of this connection? If so, do we want to refer to alternative sources of best practices that we base ourselves on? Or do we want to keep the connection alive? It does feel strange for us to suggest one practice in text and another in template.