DOC: Update description of the Cauchy cdf and its complement. #553

Job	Run time
posix (Collect coverage special_fun, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, special_...	15m 42s
posix (Collect coverage distribution_tests, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, d...	8m 17s
posix (Collect coverage mp, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, mp)	9m 29s
posix (Collect coverage misc, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, misc)	7m 47s
posix (Collect coverage quadrature, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, quadrature)	7m 22s
posix (Collect coverage interpolators, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, interp...	3m 23s
posix (Collect coverage autodiff, yes, gcc-12, 20, ubuntu-22.04, g++-12-multilib, 64, autodiff)	3m 0s
	55m 0s

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