Fix [a0d6ef020b]: Documentation bugs #1499

Job	Run time
build (gcc)	2m 9s
test (gcc)	4m 3s
build (gcc, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 55s
test (gcc, --disable-xft)	4m 1s
build (gcc, --disable-xft)	2m 10s
test (gcc, --enable-symbols)	3m 45s
build (gcc, --disable-xss)	2m 1s
build (gcc, --enable-symbols)	1m 12s
build (clang)	1m 49s
build (clang, CFLAGS=-DTK_NO_DEPRECATED=1)	1m 47s
build (clang, --disable-xft)	2m 19s
build (clang, --disable-xss)	1m 51s
build (clang, --enable-symbols)	1m 26s
	30m 28s

Provide feedback