test: make the man-page readable + sync

[matttbe]

The previous version was all compacted, and clearly not readable.

Add a bunch of new lines and indentations to fix that.

The new version looks more like the one from GNU coreutils now.

While at it, also add STRING1 > STRING2 and STRING1 < STRING2 that were missing but supported.

Note: this PR fixes #8362. It is similar to #9005 (with more visual changes), but here, I only focused on fixing the man page. I'm not sure adding a generic test is easy to do and that useful. More changes and tests can be added once clap-rs/clap#5900 is implemented, but I think these modifications only in the man-pages are enough for the moment.

[github-actions]

GNU testsuite comparison:

GNU test failed: tests/tail/symlink. tests/tail/symlink is passing on 'main'. Maybe you have to rebase?

[codspeed-hq]

Merging this PR will degrade performance by 4.01%

❌ 1 regressed benchmark
✅ 283 untouched benchmarks
⏩ 38 skipped benchmarks¹

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	cp_large_file[16]	367.6 µs	382.9 µs	-4.01%

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_{Comparing matttbe:test-man-readable (2b65dfd) with main (b556119)}

Footnotes

1. 38 benchmarks were skipped, so the baseline results were used instead. If they were deleted from the codebase, click here and archive them to remove them from the performance reports. ↩