ci: don't compile whole project when testing docs with Meson

Hi,

these two patches introduce a new "docs" alias into Meson and use it in our "documentation" CI jobs so that we stop compiling all of Git only to verify the generated manpages. This fixes the issue reported by Gábor in 1.

Thanks!

Patrick

To: git@vger.kernel.org Cc: SZEDER Gábor szeder.dev@gmail.com

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{ "series": { "revision": 1, "change-id": "20250911-b4-pks-meson-docs-target-56d8a21e84bf", "prefixes": [] } }

Closes Documentation CI job compiles all of Git with M... (#592 - closed).