[expr.mul] Reword 'truncation towards zero' in footnote

Author: Eisenwave

source/expressions.tex

@@ -6231,7 +6231,8 @@
 For integral operands, the \tcode{/} operator yields the algebraic quotient with
 any fractional part discarded;
 \begin{footnote}
-This is often called truncation towards zero.
+Discarding the fractional part is rounding towards zero.
+This rounding mode is often called truncation.
 \end{footnote}
 if the quotient \tcode{a/b} is representable in the type of the result,
 \tcode{(a/b)*b + a\%b} is equal to \tcode{a}; otherwise, the behavior