Add release changelogs for v0.28.0

[curquiza]

Here are the huge changelogs for the v0.28.0 release

⚠️ Should NOT be merged before the official v0.28.0 release is out!

[dichotommy]

It's my first time editing a release changelog in a while, so I wasn't sure if I should edit things like the header levels.

On the docs we try never to use multiple H1s in the same article, or to skip a header number (i.e. don't jump from H1 to H3). But this may be an aspect of your template, so feel free to ignore those particular suggestions.

[dichotommy]

LGTM 😎

[gmourier]

Waiting for the last naming changes if needed on meilisearch/specifications#157 before giving a final review. Other than that, everything looks great to me!

[curquiza]

@gmourier I let this PR open until the official v0.28.0 is out. I've updated the PR description to make my expectations clearer

[gmourier]

LGTM!

[gmourier]

Suggested change

	<!-- The following line should NOT be put in the official release changelogs -->
	⚠️ Since this is a release candidate (RC), the official documentation is not updated yet, but will be ready for the official v0.28.0 release. The work-in-progress documentation is available [here]().

[gmourier]

So you can remove it directly from github before the release 🤓

[curquiza]

I will not remove it from this PR, so that I can copy/paste in my next release changelog
However I will not put it in the v0.28.0 changelog on Monday haha