[Distutils] Amend PEP 440 with Wider Feedback on Release Candidates

[Donald Stufft]

I’ve had a number of people complain that PEP 440 normalizes a release
candidate as 1.0c1 instead of 1.0rc1. Do we want to ammend the PEP to switch
the normalization around so that it normalizes 1.0c1 to 1.0rc1? This probably
matches what people expect better in general? It wouldn't have any effect on
sort order or the like, it would just change which form is preferred.

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Donald Stufft
PGP: 7C6B 7C5D 5E2B 6356 A926 F04F 6E3C BCE9 3372 DCFA