Cleanup changelog formatting

[nuclearsandwich]

Description

Update changelog formatting to meet standards and pass markdown-link-check.

Links to tickets.chef.io no longer resolve, causing failures in the markdown-link-check linter. I have removed those links but preserved the bug numbers in case there's an archive of those floating around somewhere.

I also updated some recent changelog entries which were created by automation to use the bullet-list markdown formatting preferred for changelog entries.

Check List

• [x] A summary of changes made is included in the CHANGELOG under ## Unreleased
  • The changes here are meta and I don't think they merit their own changelog entry
• New functionality includes testing.
  • No new functionality has been added.
• New functionality has been documented in the README if applicable.
  • No new functionality has been added.

[ramereth]

@nuclearsandwich don't forget to actually add an entry under unreleased for this PR

[nuclearsandwich]

@nuclearsandwich don't forget to actually add an entry under unreleased for this PR

I had written in the PR description that since the changes were "meta" and minor I didn't think they merited a changelog entry. But I don't feel strongly about it if you think I should add one.

[damacus]

@nuclearsandwich without a new entry in the changelog under unreleased there won't be a new entry under the new release. Which will funnily enough make the changelog look ugly again 😆

[nuclearsandwich]

@nuclearsandwich without a new entry in the changelog under unreleased there won't be a new entry under the new release. Which will funnily enough make the changelog look ugly again laughing

Thanks for the context. I can't quite bring myself to say "makes sense" but I understand. Entry added in c1788d3

[kitchen-porter]

Released as: 9.5.16