doc: update wrongly formatted alert in nixpkgs README.md

TomRomeo ca66a204 6fedf178

Changed files
+2 -2
pkgs
+2 -2
pkgs/README.md
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For PRs with multiple commits, the PR title should be a general summary of these commits.
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[!NOTE]
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Marking a PR as a draft does not prevent automatic builds.
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> [!NOTE]
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> Marking a PR as a draft does not prevent automatic builds.
## Category Hierarchy
[categories]: #category-hierarchy