Rewrite description of old editions to include brief release notes

[magnusbaeck]

Description

The GitHub releases of the Eiffel editions don't have a very useful description; just general boilerplate and a link to versioning.md. We should update the existing releases to include a brief description of what changes went into the edition, similar to what's in the table in, yes, versioning.md.

Motivation

The description of GitHub releases are generally used for release notes (at least in short form) and we should stick to that. While the information is available from versioning.md that we link to from the release description, it's not obvious from the text ("See Versioning for more information on Eiffel protocol versioning.") that such is the case.

Exemplification

Anyone wanting to get an overview of what's happened in the Eiffel editions would probably start with the GitHub releases.

Benefits

More accessible release information.

Possible Drawbacks

Marginally more copy/paste work when preparing the release of an edition.

[magnusbaeck]

Release notes aren't generated correctly after submitting #336. I'll look into it.

[magnusbaeck]

Gah. According to https://github.com/orgs/community/discussions/50886, it's the .github/release.yml file at the tagged commit that's used when generating release notes. So the file merged in #336 will work for Orizaba and onwards but won't help us create useful release notes for old editions.

[magnusbaeck]

The list of PRs has been manually categorized for all old editions.