docs: move authentication info to separate file Goal is to reduce the gigantic 'setup' page in size, and make the information more understandable. Currently, the different topics do not really belong together. This is one small step towards that goal.

# requirements.txt file for use as "pip install -r requirements.txt" as a
# readthedocs compatible alternative to "pip install -e ." which is a working
# alternative to "setup.py develop" which doesn't work with Mercurial 3.7
.