fix doc and use of_X509v3_add_extensions() in case sk_X509_EXTENSION_… #2223

Job	Run time
basic_gcc	5m 47s
check_docs	1m 1s
check_update	1m 18s
check-ansi	2m 36s
address_ub_sanitizer	10m 39s
basic_clang	5m 55s
enable_non-default_options	4m 28s
external-test-cf-quiche	3m 30s
external-test-pyca (1.51.0, 3.9)	5m 57s
external-tests	10m 44s
full_featured	5m 57s
fuzz_tests	3m 2s
legacy	4m 32s
memory_sanitizer	18m 30s
minimal	2m 32s
no-deprecated	5m 18s
no-legacy	5m 35s
non-caching	12m 23s
no-shared-macos (macos-13)	10m 42s
no-shared-ubuntu	4m 38s
no-shared-macos (macos-14)	3m 30s
out-of-readonly-source-and-install-macos (macos-13)	13m 32s
out-of-readonly-source-and-install-ubuntu	7m 29s
out-of-readonly-source-and-install-macos (macos-14)	7m 9s
self-hosted	0s
threads_sanitizer	5m 3s
	2h 41m 47s

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