PEP 690: Added Post-History

[Kronuz]

No description provided.

[JelleZijlstra]

Should also add the discuss.python.org link.

[AA-Turner]

Suggested change

	Post-History: `03-May-2022 <https://mail.python.org/archives/list/python-dev@python.org/thread/IHOSWMIBKCXVB46FI7NGOC2F34RUYZ5Z/>`__
	Post-History: `03-May-2022 <https://discuss.python.org/t/pep-690-lazy-imports/15474>`__,
	`03-May-2022 <https://mail.python.org/archives/list/python-dev@python.org/thread/IHOSWMIBKCXVB46FI7NGOC2F34RUYZ5Z/>`__

[CAM-Gerlach]

The stated purpose of the links in the Post-History header, as reflected in its description in PEP 1, PEP 12, and the template, as well as PEP 1's Discussing a PEP section, is to be a record of the PEP's canonical Discussions-To thread(s), rather than the announcement posts on Python-Dev, and this is not how it is used on the various other PEPs that now implement it (both those with discussions on Python-Dev and Discourse).

A link to just an announcement post that repeats the information in the PEP and the thread does not seem that useful to anyone but a SC reviewer doing a final conformance check, and in that singular case can be verified with a quick search. Furthermore, at PyCon US, the SC has indicated this requirement is slated to be changed in the near future, so at least until then, I'm not sure it makes sense to propose modifying this now.

Also, while to #2467, both the Discussions-To header link text, and the hover text on Post-History entries display the item type and venue without having to parse/visit the link, I'm concerned that seemingly "duplicate" entries may be confusing and cause extra burden for users, reviewers and tools reading this field, and that users not paying careful attention may more easily navigate to, or even reply to, something that is not the canonical discussion thread; even one such reply may generated many more, and thus bifurcate the discussion and make it harder to follow for users, developers, authors and SC members alike.