README.md: improve the installation directions #182

Job	Run time
Build and test with ASAN enabled	58s
Build and test with gcc	45s
Build and test with clang	1m 19s
Build and test with gcc -m32	51s
Run shellcheck	7s
Build and test on macOS	1m 27s
Build and test with UBSAN enabled	58s
Build on Windows (MINGW32, mingw-w64-i686-gcc)	2m 13s
Build on Windows (MINGW64, mingw-w64-x86_64-gcc)	2m 10s
Fuzz with libFuzzer (wim )	2m 43s
Build on Windows (CLANG32, mingw-w64-clang-i686-clang)	2m 10s
Fuzz with wlfuzz (Linux, none)	2m 44s
Fuzz with libFuzzer (wim --asan --ubsan)	3m 2s
Build on Windows (CLANG64, mingw-w64-clang-x86_64-clang)	2m 13s
Fuzz with libFuzzer (encoding --asan --ubsan)	3m 3s
Fuzz with wlfuzz (Linux, ASAN)	3m 32s
Fuzz with libFuzzer (xmlproc )	2m 45s
Build on Windows (CLANGARM64, --install-prerequisites)	2m 13s
Fuzz with wlfuzz (Linux, UBSAN)	2m 47s
Fuzz with libFuzzer (xmlproc --asan --ubsan)	2m 54s
Fuzz with libFuzzer (xml_windows --asan --ubsan)	2m 59s
Fuzz with wlfuzz (Windows)	4m 25s
Fuzz with libFuzzer (compress )	2m 34s
Run win32-test-imagex-capture_and_apply.bat	2m 35s
Fuzz with libFuzzer (compress --asan --ubsan)	2m 56s
Fuzz with libFuzzer (decompress )	2m 39s
Fuzz with libFuzzer (decompress --asan --ubsan)	3m 11s
	1h 2m 13s

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