[Reference manual/Coq] Fix label for VERNAC EXTEND #29329

Job	Run time
Coq 8.16.1	7m 7s
Build microbenchmarks	2m 31s
Create local opam switch (macos-latest, 5)	5m 36s
Build (macos-latest, 5.1.x)	12m 18s
Create local opam switch (macos-latest, 4.14)	5m 40s
Documentation	55s
Build (ubuntu-latest, 5.1.x)	8m 29s
Format	1m 10s
Create local opam switch (ubuntu-latest, 5)	4m 55s
Build (ocaml-variants.5.3.0+trunk, ubuntu-latest, true)	1m 38s
Create local opam switch (ubuntu-latest, 4.14)	5m 4s
Build (4.14.x, ubuntu-latest, true)	1m 29s
Build monorepo benchmark docker image	3m 43s
Nix (macos-latest)	2m 1s
Build (4.14.x, macos-latest, true)	2m 21s
Nix (ubuntu-latest)	55s
Wasm_of_ocaml	10m 29s
Build (5.1.x, macos-13, true)	3m 51s
Build (ocaml-base-compiler.4.14.2,system-msvc, windows-latest)	14m 30s
Build (ocaml-base-compiler.5.1.1,system-mingw, windows-latest)	8m 21s
Build (4.08.x, ubuntu-latest, true)	1m 30s
Build (4.04.x, ubuntu-latest, true, true)	5m 32s
Build (4.02.x, ubuntu-latest, true)	3m 56s
	1h 54m 1s

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