Improve documentation #12905

Job	Run time
make (check, --disable-yjit)	10m 26s
make (check, ubuntu-24.04, capi)	10m 8s
make (test-bundled-gems)	12m 51s
make (check, i686)	16m 34s
make (check, cppflags=-DVM_CHECK_MODE)	8m 51s
make (test-bundler-parallel, 50)	22m 21s
ruby-bench (--warmup=1 --bench=1 --excludes=shipit)	14m 10s
make (check, --enable-shared --enable-load-relative)	8m 6s
make-ibm	-1s
Ubuntu result	3s
	1h 43m 29s

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