Add .pypirc specification

[bhrutledge]

Closes #730.

I'm starting this out as a draft PR, because I think a complete PR would include updates to other documents that reference .pypirc. However, before spending time on that, I'd like get the content of this document approved.

[stdedos]

LGTM from user's perspective.

Also clears up how the "don't save your token in plaintext" wizardry works

[bhrutledge]

To see the rendered version without building locally, check out:

https://bhrutledge-ppug.bhrutledge.now.sh/specifications/pypirc.html

[stdedos]

Thank you for the extra mile!

Also in-line rendering looks good enough to get rendered text display

[bhrutledge]

@di I hope you'll forgive the nudge, but I'd appreciate your thoughts on this before I link to it from other parts of the guide. And, ultimately, it'd be nice to resolve pypa/twine#638.

[di]

@bhrutledge On my list for today.

[di]

Changes LGTM, only one suggestion & a reiteration of a previous comment.

[merwok]

For reference, here is the distutils documentation about .pypirc before it was deleted from the CPython repo: https://github.com/python/cpython/blob/v3.4.10/Doc/distutils/packageindex.rst#the-pypirc-file

[bhrutledge]

For reference, here is the distutils documentation about .pypirc before it was deleted from the CPython repo

Thanks! I actually started with that, then updated/expanded it.

[di]

LGTM!

[di]

Any other @pypa/packaging-user-guide-editors want to review?