docs: remove some references to Pylons These references are either not used, or do not provide value. The Windows installation and email pages still references documents from the Pylons website -- alternative pages from Turbogears2 need to be found.

# 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
.