[expr.mul] Reword 'truncation towards zero', turn tutorial-like wording into note

Author: eisenwave

source/expressions.tex

@@ -6228,14 +6228,14 @@
 \indextext{zero!undefined division by}%
 If the second operand of \tcode{/} or \tcode{\%} is zero, the behavior is
 undefined.
-For integral operands, the \tcode{/} operator yields the algebraic quotient with
-any fractional part discarded;
-\begin{footnote}
-This is often called truncation towards zero.
-\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
+For integral operands, the \tcode{/} operator yields the algebraic quotient
+rounded towards zero.
+\begin{note}
+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
 of both \tcode{a/b} and \tcode{a\%b} is undefined.
+\end{note}
 
 \rSec2[expr.add]{Additive operators}%
 \indextext{expression!additive operators}%