Update README to include information about help2man #323

Job	Run time
Ubuntu 24.04 (g++ with sanitizers)	5m 56s
Ubuntu 24.04 (clang++ with sanitizers)	5m 2s
Ubuntu 22.04 (g++)	1m 29s
Ubuntu 22.04 (clang++)	1m 51s
	14m 18s

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