docs: correct some man pages to avoid duplicates #831

Job	Run time
rip-and-test	44m 41s
htmldocs	8m 46s
package-arch (debian:bullseye)	1m 28s
package-indep (debian:bullseye)	1m 26s
package-indep (debian:bookworm)	1m 23s
rip-and-test-clang	30m 57s
package-indep (debian:sid)	1m 27s
package-arch (debian:bookworm)	1m 24s
package-arch (debian:sid)	1m 27s
	1h 32m 59s

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