Update docs by not using is_aggregate (fixes #158) and by describing … #315

Job	Run time
windows (msvc-14.0, 14,latest, 32,64, windows-2019, -j3)	3m 23s
posix (gcc-12, 03,11,14,17,2a, ubuntu-22.04, cxxflags=--coverage -fsanitize=address,leak,undefine...	7m 31s
windows (gcc, 03,11,14,17,2a, 64, windows-2019, -j3)	8m 9s
posix (gcc-11, 03,11,14,17,2a, ubuntu-22.04, cxxflags=--coverage -fsanitize=address,leak,undefine...	6m 8s
windows (msvc-14.3, 20,latest, 64, windows-2022, -j1)	13m 52s
posix (gcc-10, 03,11,14,17,2a, ubuntu-22.04, cxxflags=--coverage -fsanitize=address,leak,undefine...	7m 40s
windows (clang-win, 14,17,2a,latest, 32,64, windows-2022)	21m 55s
posix (gcc-9, 03,11,14,17,2a, ubuntu-22.04, cxxflags=--coverage -fsanitize=address,leak,undefined...	5m 54s
posix (clang-14, 03,11,14,17,20, ubuntu-22.04)	6m 31s
posix (clang-13, 03,11,14,17,20, ubuntu-22.04)	6m 37s
finish	0s
	1h 27m 40s

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