build_docs: README update #42

Job	Run time
macos (macos-12, auto_index contract)	1h 58m 43s
windows (windows-2019)	2h 10m 34s
macos (macos-12, contract, --boostrelease)	1h 44m 19s
linux (ubuntu-latest, ubuntu:24.04, python-is-python3, auto_index)	1h 14m 16s
windows (windows-2022)	2h 4m 59s
linux (ubuntu-latest, ubuntu:22.04, python2, auto_index)	1h 12m 53s
windows (windows-2019, -boostrelease)	1h 42m 2s
macos (macos-14, auto_index contract)	1h 3m 58s
linux (ubuntu-latest, ubuntu:20.04, python, auto_index)	1h 13m 46s
windows (windows-2022, -boostrelease)	1h 35m 55s
linux (ubuntu-latest, ubuntu:24.04, python-is-python3, --boostrelease)	1h 1m 59s
macos (macos-14, contract, --boostrelease)	42m 59s
linux (ubuntu-latest, ubuntu:22.04, python2, --boostrelease)	54m 31s
linux (ubuntu-latest, ubuntu:20.04, python, --boostrelease)	1h 2m 20s
	19h 43m 14s

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