Add changelogs to all standards

[encukou]

It would be good to add a “History” section to all PyPA specifications, like the one in direct-url.
Even with a single entry, the section is useful -- to set expectations for future updates.
Please add dates if the spec isn't versioned in another way.
See discussion on Discourse.

[pfmoore]

For anyone interested in this, the biggest part is likely to be the research to find dates when decisions happened and changes were made, and links to the appropriate posts recording the decisions. For newer specifications, the information will likely be in the packaging category on Discourse but for the older ones, you'll probably need to dig around in the distutils-sig archives. Github history of the spec page itself is likely a good starting point for getting dates to guide the search.

[jeanas]

I agree that dates throughout would be useful, since they may be relevant to users when they wonder how recent the tool must be to support feature X or Y.

IMHO, we don't need the PEP approval messages because they're already recorded on the PEP's page (or should be); OTOH, links to discussions other than PEPs are useful.