Minor doc fixes (one requires verification) #2764

Job	Run time
macOS-x86 Clang with BLAS (x2)	19m 40s
macOS-M1, Clang (x3)	8m 7s
GCC build regression check (no tests)	1m 4s
Alpine Linux, musl, 32-bit (assert, x1.5)	13m 53s
MinGW GCC (x0.5)	10m 23s
MSVC (x1)	8m 47s
Ubuntu Clang with examples (x5)	12m 43s
Nemo.jl (temporary branch)	12m 23s
Ubuntu GCC with NTL (assert, x2)	8m 25s
Ubuntu GCC, Code Coverage (x10)	30m 21s
	2h 5m 46s

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