fixup: use \brk{} to deal with overfull hbox

Co-authored-by: Jan Schultke <[email protected]>

Author: dietmarkuehl

source/exec.tex

@@ -6337,7 +6337,7 @@
 \pnum
 \returns
 A \tcode{task} object whose member \exposid{handle} is
-\tcode{coroutine_handle<promise_type>::\linebreak from_promise(*this)}. % avoid Overfull
+\tcode{coroutine_handle<promise_type>::\brk{}from_promise(*this)}.
 \end{itemdescr}
 
 \begin{itemdecl}