Added a conda environment that works on (my) mac, and propose some changes in the docs

Some small issues: a space in a Makefile, some issues with the Markdown one name change proposal for the env. And a conda env for my M3 mac.

One thing I haven't got to work is (I think) the static directory, so the page looks quite awful (and I am missing any non-text buttons). So keeping this on draft in case the problem does not exist between keyboard and chair...