Fix [a0d6ef020b]: Documentation bugs #504

Job	Run time
build (gcc)	1m 43s
build (gcc, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 38s
build (gcc, --disable-xft)	1m 44s
build (gcc, --disable-xss)	2m 11s
build (gcc, --enable-symbols)	1m 19s
build (clang)	1m 56s
test (gcc)	3m 59s
test (gcc, --disable-xft)	4m 4s
build (clang, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 51s
test (gcc, --enable-symbols)	3m 34s
build (clang, --disable-xft)	1m 53s
build (clang, --disable-xss)	1m 56s
build (clang, --enable-symbols)	1m 27s
	29m 15s

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