Use American spelling of "behavior".

etc/etags.1

@@ -236,12 +236,12 @@ Don't do any more regexp matching on the following files.  May be
 freely intermixed with filenames and the \fB\-\-regex\fP option.
 .TP
 .B \-t, \-\-typedefs
-Record typedefs in C code as tags.  Since this is the default behaviour
+Record typedefs in C code as tags.  Since this is the default behavior
 of \fBetags\fP, only \fBctags\fP accepts this option.
 .TP
 .B \-T, \-\-typedefs\-and\-c++
 Generate tag entries for typedefs, struct, enum, and union tags, and
-C++ member functions.  Since this is the default behaviour
+C++ member functions.  Since this is the default behavior
 of \fBetags\fP, only \fBctags\fP accepts this option.
 .TP
 .B \-u, \-\-update