Add "coqdoc_header" and "coqdoc_footer" fields. #29123

Job	Run time
Nix (macos-latest)	2m 51s
Build (macos-latest, 5.1.x)	13m 50s
Nix (ubuntu-latest)	57s
Build (ubuntu-latest, 5.1.x)	8m 39s
Build (ocaml-variants.5.3.0+trunk, ubuntu-latest, true)	1m 30s
Coq 8.16.1	7m 15s
Coverage (5.1.x)	9m 33s
Create local opam switch (macos-latest, 5)	5m 25s
Build (4.14.x, ubuntu-latest, true)	1m 27s
Build (4.14.x, macos-latest, true)	2m 14s
Create local opam switch (macos-latest, 4.14)	8m 12s
Format	1m 12s
Build (5.1.x, macos-13, true)	3m 33s
Create local opam switch (ubuntu-latest, 5)	5m 1s
Documentation	55s
Build (ocaml-base-compiler.4.14.2,system-msvc, windows-latest)	14m 14s
Create local opam switch (ubuntu-latest, 4.14)	4m 56s
Build (ocaml-base-compiler.5.1.1,system-mingw, windows-latest)	8m 8s
Build monorepo benchmark docker image	4m 3s
Wasm_of_ocaml	10m 35s
Build microbenchmarks	2m 33s
Build (4.08.x, ubuntu-latest, true)	1m 32s
Build (4.04.x, ubuntu-latest, true, true)	4m 38s
Build (4.02.x, ubuntu-latest, true)	4m 8s
	2h 7m 21s

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