Add NEWS.md, a human-readable list of changes

[malept]

As mentioned in #235 (comment) and #223 (comment).

Only contains changes from 5.2.0 onward. If someone else wants to backfill, feel free 😁

[malept]

Opinions on whether to actually link the PRs? I kind of wish GitHub would automatically do so.

[kfranqueiro]

If we were to use GitHub's releases feature instead of add a file to the repo ourselves, it automatically links issues there.

[malept]

I propose we do both. This way the person tagging the release is not on the hook to gather the release notes, it should be gathered as changes are added.

[kfranqueiro]

FWIW, any contributor is able to create or edit a release draft on github at any time to keep track of release notes ahead of an actual release; e.g. with dgrid I try to keep a draft updated as each thing gets merged. Just have to be careful not to prematurely click the big green button on the page (why do they have to always have tempting big green buttons?!)

Not sure if that influences your thought of doing both a NEWS.md and github release notes.

[malept]

Just have to be careful not to prematurely click the big green button on the page (why do they have to always have tempting big green buttons?!)

Yeah, today I already accidentally clicked the "close PR" button.

The nice thing about the NEWS.md approach is that a user can tell what's unreleased - using just GitHub Releases doesn't really help with that use case. I have needed to figure out if feature X has been released or not when responding to issues.

[malept]

I added GitHub compare links to the version names, but for whatever reason, the diffs aren't quite right.