docs: update man page for H.264 stuff #2278

Job	Run time
cppcheck	5m 6s
code formatting check	34s
min features with gcc	2m 23s
min features with g++	2m 40s
min features with clang	2m 35s
max features with gcc	3m 58s
max features with g++	2m 41s
max features with clang	4m 8s
max features with clang and AddressSanitized	3m 29s
max features with gcc and DEBUG	3m 8s
max features with gcc for 32-bit arch (legacy OS)	2m 19s
max features with g++ for 32-bit arch (legacy OS)	2m 6s
max features with clang for 32-bit arch (legacy OS)	2m 16s
	37m 23s

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