[exec.snd.expos] Add missing space (#7785)

Author: lprv

source/exec.tex

@@ -1580,7 +1580,7 @@
 \begin{itemize}
 \item \tcode{\libconcept{semiregular}<Tag>}
 \item \tcode{\exposconcept{movable-value}<Data>}
-\item \tcode{(\libconcept{sender}<Child> \&\&...)}
+\item \tcode{(\libconcept{sender}<Child> \&\& ...)}
 \end{itemize}
 
 \pnum