The existing docs seem to assume that the user is familiar with the
history of packaging in the Python ecosystem (or at least know what is
`distutils`).
Since that is not always the case and that `distutils` is in the process
of being adopted by `setuptools`, the documentation should be changed
to minimize mentions to `distutils` and avoid expecting too much
knowledge from the users.
The benefit of this approach is that it can make the docs more
accessible and easier to understand.
Changes:
- Modify landing page to clarify what `setuptools` does (making it more
clear to understand for beginners).
- Remove mentions to `distutils`, `transition to PEP 517` from
`userguide/index`.
- Instead the text is changed to have a more "introductory" tone.
- Remove mentions to `distutils` from the Quickstart.
- Remove `python2` from the intersphinx mapping - it was causing trouble
redirecting glossary terms to Python2 docs, instead of Python3.
- Modify documentation about development mode to be more aligned with
current practices (i.e. using `pip install -e .`)
- In this process all documentation about running `setuptools` commands
in `distutils` projects was moved to a new file in `docs/deprecated/running_commands.rst`