enabled and mitigated `-Wdocumentation` and `-Wdocumentation-unknown-command` Clang compiler warnings #1568

Job	Run time
cppcheck	14m 35s
code formatting check	33s
min features with gcc	2m 25s
min features with g++	2m 49s
min features with clang	3m 12s
max features with gcc	4m 27s
max features with g++	2m 41s
max features with clang	2m 8s
max features with gcc and DEBUG	2m 29s
max features with gcc for 32-bit arch (legacy OS)	2m 9s
max features with g++ for 32-bit arch (legacy OS)	2m 37s
max features with clang for 32-bit arch (legacy OS)	1m 46s
	41m 51s

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