fix: links to release notes of previous versions

[Semoar]

The "current" docs only have the changes of the current version. Thus explicitly need to link to the old docs.

Can't add v1.10 yet, as that URL is not working. As soon as 1.11 comes out, the 1.10-links will probably break and need to be updated.

[virtualroot]

Thanks for the pull request!

We have lychee to help us find broken links, but it seems it won't catch these unless we run it with the --include-fragments flag. I'll try that.

I'm merging and let's look at 1.10 once 1.11 is out.