Document elf2tag script #2640

Job	Run time
linux-x86_64-autotools	1m 7s
linux (i386, i686, i686-linux-gnu, i386-linux-gnu)	1m 20s
linux-x86_64	1m 28s
linux (armhf, armhf, arm-linux-gnueabihf, arm-linux-gnueabihf)	1m 30s
macos-x86_64	56s
macos-x86_64-autotools	1m 0s
linux (arm64, aarch64, aarch64-linux-gnu, aarch64-linux-gnu)	1m 28s
mingw (mingw64, x86_64)	3m 29s
msvc (x86, Win32)	2m 0s
mingw (ucrt64, ucrt-x86_64)	3m 46s
msvc (x64, x64)	2m 37s
mingw (clang64, clang-x86_64)	2m 41s
msvc (arm64, ARM64)	2m 3s
	25m 25s

Provide feedback