Add Doxygen build instructions to docs/README.md (#416) #2545

Job	Run time
clang-format	12s
python-lint	5s
ubuntu-clang-build (ubuntu-24.04)	1m 16s
ubuntu-gcc-build (ubuntu-24.04-arm)	3m 35s
windows-clang-build	3m 52s
ubuntu-gcc-build (ubuntu-24.04)	1m 20s
macos-clang-build	2m 17s
windows-msvc-build	3m 2s
ubuntu-clang-build (ubuntu-24.04-arm)	1m 40s
macos-clang-test	3m 18s
windows-msvc-test	2m 11s
macos-clang-test-extended	1m 51s
ubuntu-clang-sanitizer-build (ubuntu-24.04)	1m 12s
ubuntu-clang-test (ubuntu-24.04)	3m 8s
ubuntu-clang-test (ubuntu-24.04-arm)	56s
ubuntu-gcc-test (ubuntu-24.04)	3m 24s
ubuntu-gcc-test (ubuntu-24.04-arm)	2m 32s
windows-clang-test	1m 26s
windows-msvc-test-extended	1m 24s
ubuntu-clang-sanitizer-test (ubuntu-24.04)	2m 40s
windows-clang-test-extended	1m 17s
ubuntu-clang-test-extended	-1s
ubuntu-gcc-test-extended	0s
ubuntu-gcc-build-codecov	0s
ubuntu-clang-sanitizer-test-extended (ubuntu-24.04)	2m 25s
ubuntu-gcc-build-perf-stats	0s
	45m 2s

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