[pairs.pair, tuple.cnstr] Change 'behaviour' to 'behavior' (#1136)

Fixes #1128.

Author: jfbastien

source/utilities.tex

@@ -953,11 +953,11 @@
 This constructor shall not participate in overload resolution unless
 \tcode{is_default_construct\-ible_v<first_type>} is \tcode{true} and
 \tcode{is_default_constructible_v<second_type>} is \tcode{true}.
-\begin{note} This behaviour can be implemented by a constructor template
+\begin{note} This behavior can be implemented by a constructor template
 with default template arguments. \end{note}
 The constructor is explicit if and only if either \tcode{first_type} or
 \tcode{second_type} is not implicitly default-constructible.
-\begin{note} This behaviour can be implemented with a trait that checks
+\begin{note} This behavior can be implemented with a trait that checks
 whether a \tcode{const first_type\&} or a \tcode{const second_type\&}
 can be initialized with \tcode{\{\}}. \end{note}
 \end{itemdescr}
@@ -1610,11 +1610,11 @@
 \remarks
 This constructor shall not participate in overload resolution unless
 \tcode{is_default_construct\-ible_v<$T_i$>} is \tcode{true} for all $i$.
-\begin{note} This behaviour can be implemented by a constructor template
+\begin{note} This behavior can be implemented by a constructor template
 with default template arguments. \end{note}
 The constructor is explicit if and only if $T_i$ is not implicitly
 default-constructible for at least one $i$.
-\begin{note} This behaviour can be implemented with a trait that checks whether
+\begin{note} This behavior can be implemented with a trait that checks whether
 a \tcode{const $T_i$\&} can be initialized with \tcode{\{\}}. \end{note}
 \end{itemdescr}