docs: add changelog

[ThomasFrans]

closes #1296

[ThomasFrans]

I've had this in a private fork for some time since I wanted to see what it looked like but wanted to wait for input on #1296. The stupid GitHub bot keeps bugging me about outdated dependencies and I don't know how to turn it off in a private repo, so I'm just making this PR and removing that fork because the barrage of mails it's sending is driving me insane 😄.

This was just for me to see what could be put in the changelog, but I think it looks pretty good and gives a handy overview for any users that are interested in what happened with the project over time. It's not finished yet. If this would be considered, it could be nice to add some contribution instructions that explain the contribution process and all the steps before creating a PR (formatting, clippy and adding user-facing changes to the changelog). I would also want to maintain the changelog but as I explained in #1296, I think it's less error prone to add the changes together with the commits that introduce them.

The changelog included with this PR isn't complete, but I don't think it's a requirement to go all the way back to 0.1.0. As long as the changes are included from the point when the changelog was added, it should be fine, as it's mostly for keeping up to date with changes and documenting breaking stuff (especially after a 1.0.0 release).

[hrkfdn]

I like it a lot, thanks! I think adding a PR template makes sense to remind people to update the changelog (and READMEs). I added something simple, as I think complex/large PR templates can be rather intimidating. WDYT?

[ThomasFrans]

Glad to hear. I think the template should be as friction-free as possible like you say. It shouldn't scare new contributors (or maybe even first time contributors to any project). One tiny change I would make is to say what belongs in the changelog. It's not immediately clear that developer-facing changes are best left out.

[ThomasFrans]

I added some more versions to the changelog to flesh it out. I also added a bit more info to the changelog part of the PR template to try and prevent developer jargon from being added to the changelog.

I noticed that the PR template mentions 'requesting a review', but I don't think that's possible for normal contributors, so that might need to be removed.

[hrkfdn]

I noticed that the PR template mentions 'requesting a review', but I don't think that's possible for normal contributors, so that might need to be removed.

True, to me opening a PR is somewhat synonymous to requesting a review, but I will simplify the wording.

EDIT: On second thought I think it's fine. The other wording I came up with is "Checklist before opening a PR" and doesn't feel right, as people are free to open draft PRs that aren't fully fledged. Will merge this PR now, thanks again :)

[ThomasFrans]

I guess that's also fine. I just thought it would be confused with the 'request a review' feature of GitHub, which normal people don't have access to, but it might be clear enough that that's not what the template refers to.