doc: sphinx-lint: fix dangling-hyphen

Dangling hyphens at the end of a line are usually a problem, ie. you
have an "hyphenated-word" and breaking it on two line will render it as
"hyphenated- word".
This commit fixes the few occurences of such dangling hyphens.

Signed-off-by: Benjamin Cabé <benjamin@zephyrproject.org>