[Chore] Fix 'out of scope' haddock warnings

Description

Problem: when building documentation, there are quite a few haddock warnings generated.

Solution: Fix references in haddocks. Use non-linking syntax if that is impossible or non-applicable.

I did add some missing haddocks while at it, but it definitely wasn't the focus. I'd like to get these pesky warnings out of the way first.

Related issue(s)

Some work towards TM-114

✅ Checklist for your Merge Request

Related changes (conditional)

N/A

• Tests (see short guidelines)

  • If I added new functionality, I added tests covering it.
  • If I fixed a bug, I added a regression test to prevent the bug from silently reappearing again.

• Documentation

  • I checked whether I should update the docs and did so if necessary:
    • Root README and other README.md files
    • Haddock
    • docs/
  • I updated changelog files of all affected packages released to Hackage if my changes are externally visible.

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