Show release notes when running self-update command

[filiptibell]

Right now the self-update subcommand only shows the latest version that was updated to:

🚀 Rokit has been updated successfully!

You are now running version a.b.c, updated from x.y.z.

It might be useful to show release notes for the new version, or all versions between the old and new. Rokit already fetches full release information for self-updating, which includes the release description, it is just left unused.

• Release notes may be quite long, it could be a good idea to prompt the user (Do you want to view release notes for a.b.c?) before showing them.
• Showing release notes with pretty formatting (bolding) would make this more useful, and also require parsing markdown. This parsing is typically not too complicated but may increase Rokit's binary size.