Add option to show a link to the release notes

[hverlin]

This is a feature request. See https://github.com/jdx/mise/discussions/4241 for more context.

This is a feature request in having an option to either customize what's shown in the prompt or show a link to the release notes. I believe that if one is using GitHub releases, it might be very convenient to always show the link so that the user does not have to look for the release notes.

I am not sure what the API would look like here, maybe allowing a custom link (e.g. to a website with the changelog or changelog.md) or having an option to automatically get the link to the release notes. (for example, in the context of mise, it would be handy to show a link to either https://github.com/jdx/mise/releases or https://github.com/jdx/mise/releases/tag/v2025.1.15).