docs: improve and simplify changelog

[ThomasFrans]

Remove implementation details from the changelog as they are provided by the link in the version title for each release. Also rephrase some changes to make them more clear.

Describe your changes

• Correctly add links at the bottom so the titles lead to the actual changes
• Rephrase some stuff to make it more clear to non-developers
• Remove implementation details (things a user wouldn't see in the program, documentation or the CLI for ncspot)

Issue ticket number and link

/

Checklist before requesting a review

• Documentation was updated (i.e. due to changes in keybindings, commands, etc.)
• Changelog was updated with relevant user-facing changes (eg. not dependency updates,
  not performance improvements, etc.)

[ThomasFrans]

This is not meant as a way to remove meaningful contributions from being shown to end users. The changelog should just not contain implementation details because non-developers don't care about those, despite how meaningful they are. If they are included, the changelog loses its entire purpose 🙂 (that's what the links to the commit history are for)

[hrkfdn]

Merged, thanks!