[Merged by Bors] - doc: add newlines to clarify paragraph breaks

[grunweg]

These are strictly speaking, required by markdown, and make it more clear to the reader that a new paragraph begins. This corrects some generated documentation entries to have proper paragraph breaks.

Found by the linter in #27897.

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[grunweg]

@harahu You may find this interesting.

[github-actions]

PR summary 424dce2f30

Import changes for modified files

No significant changes to the import graph

Import changes for all files

Files	Import difference

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Declarations diff

No declarations were harmed in the making of this PR! 🐙

You can run this locally as follows

## from your `mathlib4` directory:
git clone https://github.com/leanprover-community/mathlib-ci.git ../mathlib-ci

## summary with just the declaration names:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh <optional_commit>

## more verbose report:
../mathlib-ci/scripts/pr_summary/declarations_diff.sh long <optional_commit>

The doc-module for scripts/pr_summary/declarations_diff.sh in the mathlib-ci repository contains some details about this script.

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No changes to strong technical debt.

No changes to weak technical debt.

[harahu]

These are strictly speaking, required by markdown [...]

Not merely strictly speaking! If you check the documentation pages, you'll find that this PR corrects actual misrenderings.

Thanks for tagging me, I am very very happy to see this work.

[grunweg]

@JovanGerb Would you like to review this PR?

[JovanGerb]

Looks reasonable to me

maintainer merge

[github-actions]

🚀 Pull request has been placed on the maintainer queue by JovanGerb.

[bryangingechen]

Thanks!
bors r+

[mathlib-bors]

Pull request successfully merged into master.

Build succeeded:

• ci (staging) / Build
• ci (staging) / Lint style
• ci (staging) / Post-Build Step
• ci (staging) / Post-CI job