CWG2650 Incorrect example for ill-formed non-type template arguments

The change from "struct" to "class" is accidentally missing from the
paper P2710R0, but it was intended as part of the issue resolution, as
confirmed by CWG.

Fixes NB US 068 (C++23 CD).

Author: burblebee

source/templates.tex

@@ -7329,9 +7329,11 @@
 \begin{example}
 \begin{codeblock}
 template <class T, T> struct S {};
-template <class T> int f(S<T, T()>*);
-struct X {};
-int i0 = f<X>(0);
+template <class T> int f(S<T, T{}>*);   // \#1
+class X {
+  int m;
+};
+int i0 = f<X>(0);   // \#1 uses a value of non-structural type \tcode{X} as a non-type template argument
 \end{codeblock}
 \end{example}