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

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