[expr.const.cast] Fix punctuation placement.

Author: tkoeppe

source/expressions.tex

@@ -4225,7 +4225,7 @@
 \pnum
 \begin{note}
 Some conversions which involve only changes in cv-qualification cannot
-be done using \tcode{const_cast.} For instance, conversions between
+be done using \tcode{const_cast}. For instance, conversions between
 pointers to functions are not covered because such conversions lead to
 values whose use causes undefined behavior. For the same reasons,
 conversions between pointers to member functions, and in particular, the