add documentation for GENERAL_NAME_create() #1362

Job	Run time
run-checker (enable-asan enable-ubsan no-shared no-asm -DOPENSSL_SMALL_FOOTPRINT)	10m 20s
run-checker (no-ct)	5m 5s
run-checker (no-dso)	4m 56s
run-checker (no-dynamic-engine)	5m 9s
run-checker (no-ec2m)	5m 3s
run-checker (no-engine no-shared)	4m 40s
run-checker (no-err)	5m 17s
run-checker (no-filenames)	6m 19s
run-checker (enable-ubsan no-asm -DOPENSSL_SMALL_FOOTPRINT -fno-sanitize=alignment)	7m 55s
run-checker (no-module)	5m 6s
run-checker (no-ocsp)	5m 1s
run-checker (no-pinshared)	5m 13s
run-checker (no-srp)	5m 9s
run-checker (no-srtp)	5m 16s
run-checker (no-ts)	5m 17s
run-checker (enable-weak-ssl-ciphers)	5m 8s
run-checker (enable-zlib)	5m 16s
	1h 36m 10s

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