Make doxygen generate a spy.tag in the doc files #58

Job	Run time
macosx (clang, x86_osx, Debug)	5s
wasm (clang, wasm, Debug)	1m 8s
macosx (clang, x86_osx, Release)	5s
wasm (clang, wasm, Release)	1m 7s
clang (clang, x86, Debug)	1m 9s
clang-cl (Debug)	46s
clang (clang, x86, Release)	1m 7s
dpcpp (dpcpp, x86, Debug)	1m 7s
gcc (gcc, x86, Debug)	3s
dpcpp (dpcpp, sycl, Debug)	20s
gcc (gcc, x86, Release)	1s
clang-cl (Release)	43s
msvc (Debug)	1m 5s
gcc (gcc, aarch64, -Wno-psabi, Debug)	56s
dpcpp (dpcpp, x86, Release)	1m 8s
msvc (Release)	40s
dpcpp (dpcpp, sycl, Release)	59s
gcc (gcc, aarch64, -Wno-psabi, Release)	14s
nvcc	1m 7s
gcc (gcc, aarch64.sve, -Wno-psabi, Debug)	1m 8s
gcc (gcc, aarch64.sve, -Wno-psabi, Release)	1m 6s
riscv (clang, rvv128, Debug)	1m 6s
gcc (gcc, aarch64.sve2, -Wno-psabi, Debug)	56s
riscv (clang, rvv128, Release)	1m 7s
gcc (gcc, aarch64.sve2, -Wno-psabi, Release)	1m 6s
gcc (gcc, ppc64, -Wno-psabi, Debug)	9s
gcc (gcc, ppc64, -Wno-psabi, Release)	1s
	20m 29s

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