Improve instructions for setting up a development environment
Neither of those places mention that the simplest ways to get set up are:
conda env create -f docker/kwant-latest.yml && conda activate kwant-latest
docker build -t kwant docker/Docker.conda && docker run kwant
These instructions could also be recommended for running the latest development version of Kwant (unless we finally squash #339(
We can of course keep the esoteric instructions for people who do not want to use the Conda package manager/Docker, but IMO we should not forget that most people do not have strong opinions about what package manager to use (e.g. Debian vs Conda); they just want the simplest way to get everything working.