readme: remove incorrect "not"

[cakebaker]

With a recent commit the following sentence was added to the readme:

Use coreutils-*-musl if coreutils-*-musl is not compatible with your system.

The sentence doesn't make sense. This PR removes the "not". However, it's also possible that the "not" is correct and the second coreutils-*-musl is incorrect.

[github-actions]

GNU testsuite comparison:

Skip an intermittent issue tests/date/date-locale-hour (fails in this run but passes in the 'main' branch)
Skipping an intermittent issue tests/cut/bounded-memory (passes in this run but fails in the 'main' branch)
Note: The gnu test tests/printf/printf-surprise is now being skipped but was previously passing.
Note: The gnu test tests/tail/tail-n0f is now being skipped but was previously passing.

[codspeed-hq]

Merging this PR will degrade performance by 12.08%

❌ 2 regressed benchmarks
✅ 315 untouched benchmarks
⏩ 46 skipped benchmarks¹

Warning

Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Mode	Benchmark	BASE	HEAD	Efficiency
❌	Simulation	ls_recursive_balanced_tree[(6, 4, 15)]	48.9 ms	50.9 ms	-3.91%
❌	Memory	cp_recursive_deep_tree[(120, 4)]	562.5 KB	699.2 KB	-19.55%

Tip

Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.

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_{Comparing cakebaker:readme_fix_sentence (373d88d) with main (40c36f6)}

Footnotes

1. 46 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. ↩

[oech3]

Sorry. I typo.

[xtqqczze]

Suggested change

	Minimal compatible glibc version is same with ubuntu-latest runner. Use `coreutils-*-musl` if `coreutils-*-musl` is compatible with your system.
	Minimal compatible glibc version is same with ubuntu-latest runner. Use `coreutils-*-musl` if `coreutils-*-gnu` is not compatible with your system.

My understanding is that this was the likely intent, based on the conversation at #12005.

[xtqqczze]

I think the README should document the exact minimum supported glibc version for coreutils compatibility.