Standardise newlines after module-level docstrings

[ichard26]

Description

I resolved the merge conflicts in #2996. This PR is that PR with a few tweaks on top.

Closes #2996, resolves #1872.

Checklist - did you ...

• Add a CHANGELOG entry if necessary?
• Add / update tests if necessary?
• Add new / update outdated documentation?

[ichard26]

I should mention that @felix-hilden and I "approved" the original PR. We didn't actually mark our reviews as approving, but we liked the style change and approved of the implementation.

[github-actions]

diff-shades results comparing this PR (af30118) to main (af3de08). The full diff is available in the logs under the "Generate HTML diff report" step.

╭───────────────────────── Summary ─────────────────────────╮
│ 15 projects & 610 files changed / 715 changes [+549/-166] │
│                                                           │
│ ... out of 2 279 946 lines, 10 403 files & 23 projects    │
╰───────────────────────────────────────────────────────────╯

Differences found.

What is this? | Workflow run | diff-shades documentation

[ichard26]

This shouldn't be happening, will look into it soon.

[DanielNoord]

I attempted a new rebase without the refactoring in #3932. Please consider reviewing it so that the new formatting can go into the preview mode.

[JelleZijlstra]

@ichard26 are you still interested in this as a pure refactor? I merged #3932 which makes the behavior change.