[meta.reflection.queries] Fix typo in comment in example

Fixes NB US 96-206 (C++26 CD).

Author: jensmaurer

source/meta.tex

@@ -4039,7 +4039,7 @@
 static_assert(^^x != ^^y);                      // OK, \tcode{x} and \tcode{y} are different variables,
                                                 // so their reflections compare different
 static_assert(constant_of(^^x) ==
-              constant_of(^^y));                // OK, both \tcode{constant_of(x)} and
+              constant_of(^^y));                // OK, both \tcode{constant_of(\reflexpr{x})} and
                                                 // \tcode{constant_of(\reflexpr{y})} represent the value \tcode{0}
 static_assert(constant_of(^^x) ==
               reflect_constant(0));             // OK, likewise