Document elf2tag script #2654

Job	Run time
linux-x86_64-autotools	2m 7s
linux-x86_64	1m 48s
linux (i386, i686, i686-linux-gnu, i386-linux-gnu)	1m 32s
macos-x86_64	35s
linux (armhf, armhf, arm-linux-gnueabihf, arm-linux-gnueabihf)	1m 25s
macos-x86_64-autotools	56s
linux (arm64, aarch64, aarch64-linux-gnu, aarch64-linux-gnu)	1m 28s
mingw (mingw64, x86_64)	4m 19s
mingw (ucrt64, ucrt-x86_64)	4m 20s
msvc (x86, Win32)	2m 30s
mingw (clang64, clang-x86_64)	3m 32s
msvc (x64, x64)	2m 44s
msvc (arm64, ARM64)	2m 30s
	29m 46s

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