enabled and mitigated `-Wdocumentation` and `-Wdocumentation-unknown-command` Clang compiler warnings #1570

Job	Run time
code formatting check	22s
min features with gcc	2m 45s
cppcheck	10m 51s
min features with g++	2m 49s
min features with clang	2m 35s
max features with gcc	4m 1s
max features with g++	3m 24s
max features with clang	2m 47s
max features with gcc and DEBUG	2m 42s
max features with gcc for 32-bit arch (legacy OS)	3m 3s
max features with g++ for 32-bit arch (legacy OS)	1m 48s
max features with clang for 32-bit arch (legacy OS)	1m 41s
	38m 48s

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