[Sync to prerelease] Add pages for release notes

[github-actions[bot]]

Description

Sync of #1250 to prerelease.

Original PR

Add pages for release notes

A rather manual take on having release notes in permanent locations on quarto.org of the form quarto.org/docs/download/changelog/1.*/ (e.g. 1.4).

Available via links from "Older Releases" tab. Current and prerelease are aliased to their respective pages.

We would have to add the following tasks to the release checklist:

• Copy changelog from old release to _changelog.md in docs/download/changelog/1.x

• Copy docs/download/changelog/1.*/index.qmd and increment versions

• Add new item to download-older listing in docs/download/index.qmd

• Increment version in aliases of:

  • docs/download/release.qmd
  • docs/download/prerelease.qmd

Would close https://github.com/quarto-dev/quarto-cli/issues/5396